KR20160072521A - Power supply including llc converter and protection method for the same - Google Patents

Abstract

An embodiment provides a power supply device and a protection method thereof. The power supply device comprises: an LLC converter configured to output an input voltage as a preset output voltage by first and second switching signals; a current sensing unit configured to detect a resonance inductor current flowing in the LLC converter; and a protection circuit configured to output the resonance inductor current and a protection signal for stopping an operation of the LLC converter in correspondence with a phase difference of the first and second switching signals.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a power supply device including an LLC converter,

The present invention relates to a power supply device including an LLC converter and a protection method thereof.

 Switch mode power supplies are used in a wide range of electronic equipment. In particular, LLC converters are widely used due to their high efficiency and simple structure. The LLC converter can design resonant tank stages based on the gain curve shown in FIG. 1 using FHA (Fundamental Harmonic Approximation). In this case, the LLC converter can operate in the ZVS (zero voltage shutdown) region or the ZCS (zero voltage shutdown) region according to the impedance of the resonant tank stage. In case of operating in the ZCS region, Lt; RTI ID = 0.0 > region.

In order to operate only in the ZVS region, it is possible to set the minimum frequency and the input voltage so that the design margin enough for the gain predicted by the FHA can be provided. However, the margin may be set to be larger than the actual required margin due to the error of the FHA, and the efficiency of the LLC converter may be lowered.

Korean patent publication KR 2012-0106511 (public on September 29, 2012)

It is an object of the present invention to provide a power supply device including an LLC converter that operates with high efficiency and stability and a protection method thereof.

The first embodiment of the present invention is characterized by including: an LLC converter for outputting an input voltage with a predetermined output voltage by a first switching signal and a second switching signal; a current sensing unit for sensing a resonant inductor current flowing through the LLC converter; And a protection circuit for outputting a protection signal for stopping the operation of the LLC converter corresponding to the phase difference between the current and the first switching signal or the second switching signal.

The second embodiment of the present invention provides a method of protecting a power supply device including an LLC converter that receives a first switching signal and a second switching signal and generates a predetermined voltage, Determining a phase difference between the resonant inductor current and the first switching signal or the second switching signal and outputting a protection signal to stop the operation of the LLC converter if the phase difference is less than a predetermined value, .

According to the power supply device including the LLC converter according to the present invention and the protection method thereof, the power supply device can be designed to be optimized for efficiency, thereby reducing the switching loss and increasing the efficiency. In addition, it is possible to protect the device and to operate stably.

1 is a graph showing a gain curve of an LLC resonant tank.
FIG. 2 is a structural diagram showing a structure of a power supply device including an LLC converter using a phase according to the present invention.
3 is a circuit diagram showing an embodiment of the LLC resonant converter shown in Fig.
4 is a structural diagram showing a first embodiment of the protection circuit shown in Fig.
5 is a timing chart showing the operation of the protection circuit shown in Fig.
6 is a structural diagram showing a second embodiment of the protection circuit shown in Fig.
7 is a timing chart showing the operation of the protection circuit shown in Fig.
8 is a flowchart showing a protection operation in the LLC converter shown in Fig.

The control device according to the present invention, and the technical effect of the power source device using the same, the effect of the present invention will be clearly understood from the following detailed description with reference to the accompanying drawings.

In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. In this specification, the terms first, second, etc. are used to distinguish one element from another element, and the element is not limited by these terms.

The following detailed description of the invention refers to the accompanying drawings, which illustrate, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. It should be understood that the various embodiments of the present invention are different, but need not be mutually exclusive. For example, certain features, structures, and characteristics described herein may be implemented in other embodiments without departing from the spirit and scope of the invention in connection with an embodiment. It is also to be understood that the position or arrangement of the individual components within each disclosed embodiment may be varied without departing from the spirit and scope of the invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is to be limited only by the appended claims, along with the full scope of equivalents to which such claims are entitled, if properly explained. In the drawings, like reference numerals refer to the same or similar functions throughout the several views.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, so that those skilled in the art can easily carry out the present invention.

2 is a structural diagram showing a power supply device including an LLC converter according to the present invention.

2, the power supply 200 includes an LLC converter 210 for outputting an input voltage Vs at a preset output voltage by a first switching signal Q1 and a second switching signal Q2, A current sensing unit 220 for sensing a resonant inductor current Ir flowing through the resonant inductor current Ir and a resonant inductor current Ir corresponding to a phase difference between the first switching signal Q1 or the second switching signal Q2 And a protection circuit 230 for outputting a protection signal for stopping the operation of the LLC converter 210.

The LLC converter 210 receives the first switching signal Q1 and the second switching signal Q2 and converts the flow of the current flowing through the input voltage to convert the input voltage Vs into a predetermined output voltage (Vo). At this time, the output voltage Vo can be fed back so that the output voltage Vo can be constant. In addition, the LLC converter 210 can be operated by setting the switching frequency of the first switching signal Q1 and the second switching signal Q2 to operate in the ZVS region shown in FIG.

The current sensing unit 220 can sense the resonant inductor current Ir flowing to the LLC converter 210 by the first switching signal Q1 and the second switching signal Q2. The power supply 200 may enable the LLC converter 210 to operate in the ZVS region using the resonant inductor current Ir. The current sensing unit 220 senses the resonant inductor current Ir through the voltage applied to the sense resistor connected to the LLC converter 210 or the amount of current induced in response to the resonant inductor current Ir The resonant inductor current Ir can be detected. However, the configuration of the current sensing unit 220 is not limited thereto.

The protection circuit 230 may output a protection signal for preventing damage to the LLC converter 210 and / or for efficient driving. The protection circuit 230 uses the phase difference between the resonant inductor current Ir and the first switching signal Q1 or the resonant inductor current Ir and the second switching signal Q2 to determine whether the LLC converter 210 is in the ZVS region or the ZCS It is possible to know whether or not it operates in the area. The LLC converter 210 may operate in the ZCS region if the switching frequency is lower than the frequency at the maximum point of interest as shown in FIG. 1 and may operate in the ZVS region if the switching frequency is higher than the frequency at the maximum point of interest. Also, the LLC converter 210 may be less efficient at the maximum point. Accordingly, when the protection circuit 230 operates at the maximum number of points using the resonant inductor current Ir and the phase difference between the first switching signal Q1 or the second switching signal Q2, the protection circuit 230 outputs a protection signal to the LLC converter 210 Can be stopped. The protection circuit 230 may determine that the protection circuit 230 operates at the maximum point if there is no phase difference between the resonant inductor current Ir and the first switching signal Q1 or the second switching signal Q2.

3 is a structural diagram showing a structure of a power supply device including an LLC converter using a phase according to the present invention.

3, the LLC converter 210 may include a power converter 211, a resonant tank 212, a transformer 213, and a rectifier 214. The rectifying unit 214 may be connected to the output capacitor Co and may transmit the output voltage Vo to the load from the rectifying unit 214. [

The power conversion unit 211 includes a first switching device SW1 and a second switching device SW2 that can be turned on alternately by receiving the first switching signal Q1 and the second switching signal Q2 . The first switching device SW1 and the second switching device SW2 may be a field effect transistor (FET), a metal oxide silcon field effect transistor (MOSFET), a bipolar junction transistor (BJT), or the like. However, the present invention is not limited thereto. The resonance tank 212 may include a first inductor Lr, a second inductor Llkg, a third inductor Lm, and a resonant capacitor Cr. The transformer 213 may include a first side winding 213a and a second side winding 213b and may include an electromotive force generated by a current transmitted to the first side winding 213a by the power conversion unit 211 It is transformed by the secondary side winding 213b to output a predetermined voltage. The secondary winding 213b of the transformer 213 may include a first sub-winding and a second sub-winding and may rectify the voltage induced in the secondary winding 213b by the rectification section 214, (Co). The rectifying unit 214 includes a first diode D1 and a second diode D2 and is capable of full-wave rectification of a predetermined voltage output from the second secondary winding 213b. However, the configuration of the rectifying unit 214 is not limited to this.

The current sensing unit 220 may be connected to the first node N1 of the LLC converter 210 to receive the resonant inductor current Ir from the current sensing unit 220. [ Also, the current sensing unit 220 may receive the resonant inductor current Ir through the auxiliary winding wound on the third inductor Lm. However, the connection of the current sensing unit 220 is not limited thereto. In addition, the resonant inductor current Ir may be a current induced in the third inductor Lm.

The LLC converter 210 includes a control unit 215 and generates a first switching signal Q1 and a second switching signal Q2 at the control unit 215 and outputs the first switching signal Q1 and the second switching signal Q2 to the first switching device Q1 of the power conversion unit 211, To the first switching element SW1 and the second switching element SW2. In addition, the controller 215 can receive the driving voltage Vcc and can start driving when the enable signal enable is transmitted. The protection signal shown in FIG. 2 prevents the controller 215 from transmitting a driving voltage to the controller 215 or prevents the controller 215 from operating by preventing an enable signal from being transmitted to the LLC converter 210 The operation can be stopped.

Fig. 4 is a structural diagram showing the first embodiment of the protection circuit shown in Fig. 2, and Fig. 5 is a timing diagram showing the operation of the protection circuit shown in Fig.

Referring to FIGS. 4 and 5, the protection circuit 230a may include a first comparator 231a and an AND gate 232a. The negative input terminal of the first comparator may receive the resonant voltage corresponding to the resonant inductor current Ir sensed by the current sensing unit 220 and the positive input terminal thereof may be connected to the ground. The output of the first comparator 231a and the first switching signal Q1 may be input to the AND gate 232a, respectively.

The negative input terminal of the first comparator 231a receives the resonant voltage Vir from the current sensing unit 220. The positive input terminal of the first comparator 231a is connected to the ground, When the voltage (Vir) has a negative value, it can output a high signal. When the voltage (Vir) has a positive value, it can output a low signal. The output terminal of the first comparator 231a and the first switching signal Q1 are subjected to the end operation by the AND gate 232a and the output signal of the first comparator 231a and the first switching signal Q1 are high Only high signals can be output. 5, when the resonance voltage Vir is in phase with respect to the first switching signal Q1 and the magnitude of the resonance voltage Vir is negative, the first switching signal Q1 is in a high state The AND gate 232a can output a high signal. At this time, the signal output from the AND gate 232a may be output as a low signal when the resonance voltage Vir changes from negative to positive. Therefore, the protection circuit 230a can determine the phase difference between the first switching signal Q1 and the resonance voltage Vir through the width of the pulse generated by keeping the signal output from the AND gate 232a at a high level . If there is no phase difference between the first switching signal Q1 and the resonance voltage Vir, the signal output from the AND gate 232a is not output in a high state, and therefore, the low state can be maintained. Accordingly, when the signal output from the AND gate 232a is outputted in a low state, it can be determined that the first switching signal Q1 and the resonance voltage Vir do not have a phase difference. Therefore, the protection circuit 230a can determine the phase difference between the first switching signal Q1 and the resonant voltage Vir using the signal output from the AND gate 232a, and output the protection signal if there is no phase difference.

In addition, the protection circuit 230a may include a level converter 233a and a second comparator 234a. The output of the AND gate 232a is transmitted to the level converter 233a and the output of the level converter 233a is transmitted to the negative input terminal of the second comparator 234a and the reference voltage Vref is supplied to the second comparator 234a (+) Input terminal of the inverter. The protection circuit 230a can convert the pulse output from the AND gate 232a into a voltage at the level converter 233a and compare it with the reference voltage Vref at the second comparator 234a. The second comparator 234a of the protection circuit 230a can output a protection signal when the voltage output from the level converter 233a is smaller than the reference voltage Vref. Therefore, the protection circuit 230a can output a protection signal if the phase difference is smaller than a predetermined size even if the first switching signal Q1 and the resonance voltage Vir have a phase difference. The level converter 233a can output a pulse output from the AND gate 232a at a predetermined voltage using an RC filter.

Since the signal output from the AND gate 232a occurs only when the first switching signal Q1 and the output signal of the first comparator 231a are both high, the pulse can be generated for a very short time. If the pulse is generated for such a short time, the protection signal is outputted for most of the time, and the operation time of the LLC converter 210 may be shortened. Therefore, the above problem can be solved by causing the protection circuit 230a to operate only when a signal output from the AND gate 232a using a timer or the like holds a low signal for a predetermined time or longer. Also, if the protection circuit 230a is operated only during a period in which the first switching signal Q1 is input, the above problem can be solved. However, the present invention is not limited thereto.

Here, it is described that the resonant voltage Vir is transmitted to the negative input terminal of the first comparator 231a and the first switching signal Q1 is transmitted to the AND gate 232a. However, the present invention is not limited thereto, The phase difference can be detected even if the resonant voltage Vir is transmitted to the positive input terminal of the comparator 231a and the second switching signal Q2 is transmitted to the end gate 232a.

FIG. 6 is a structural diagram showing a second embodiment of the protection circuit shown in FIG. 2, and FIG. 7 is a timing chart showing the operation of the protection circuit shown in FIG.

Referring to FIGS. 6 and 7, the protection circuit 230b may include a first comparator 231b and an AND gate 232b. The first comparator 231b may receive the resonant voltage Vir corresponding to the resonant inductor current Ir detected by the current sensing unit 220 and the positive input terminal thereof may be connected to the ground . The output of the first comparator 231b and the second switching signal Q2 may be input to the AND gate 232b, respectively.

The negative input terminal of the first comparator 231b receives the resonant voltage Vir from the current sensing unit 220. The first comparator 231b has a negative input terminal connected to the ground, When the voltage (Vir) has a positive value, it can output a high signal. When the voltage (Vir) has a negative value, it can output a low signal.

The output terminal of the first comparator 231b and the second switching signal Q2 are subjected to the end operation by the AND gate 232b so that the output signal of the first comparator 231b and the second switching signal Q2 are high Only high signals can be output. Therefore, when the second switching signal Q2 becomes high because the phase of the resonance voltage Vir is slower than the second switching signal Q2 as shown in Fig. 7, the resonance voltage Vir continues to be positive (positive) Lt; / RTI > And, when the second switching signal Q2 is held high for a predetermined time, the resonance voltage Vir can be switched from positive to negative. Accordingly, the AND gate 232b can output a high signal in the period until the second switching signal Q2 becomes high and the resonance voltage Vir is switched to negative. Therefore, the phase difference between the second switching signal Q2 and the resonance voltage Vir can be determined through the width of the pulse generated by keeping the signal output from the AND gate 232b high. If the second switching signal Q2 and the resonance voltage do not have a phase difference, the signal output from the AND gate 232b is not output in the high state, and therefore, the low state can be maintained. Accordingly, when the low state is output, it can be determined that the second switching signal Q2 and the resonance voltage Vir do not have a phase difference. Therefore, the protection circuit 230b can determine the phase difference using the signal output from the AND gate 232b, and output the protection signal if there is no phase difference.

The protection circuit 230b may further include a duty detector 233b. The output of the first AND gate 232b is transmitted to the duty detector 233b and the pulse corresponding to the output of the first AND gate 232b is detected by the duty detector 233b. If the width of the pulse is below a predetermined width, A signal can be output. The protection circuit 230b can output a protection signal when the width of the pulse detected by the duty detector 233b is smaller than the predetermined pulse width. Therefore, the protection circuit 230b can output a protection signal if the phase difference is smaller than a predetermined size.

Since the signal output from the AND gate 232b occurs only when the output signal of the second switching signal Q2 and the output signal of the first comparator 231b are both high, a pulse can be generated for a very short time. If the pulse is generated for such a short time, the protection signal is outputted for most of the time, and the operation time of the LLC converter 210 may be shortened. Accordingly, the above problem can be solved by causing the protection circuit 230b to operate only when a signal output from the AND gate 232b using a timer or the like holds a low signal for a predetermined time or longer. In addition, the protection circuit 230b operates only during a period in which the second switching signal Q2 is input, thereby solving the above problem. However, the present invention is not limited thereto.

Here, it is described that the resonant voltage Vir is transmitted to the positive input terminal of the first comparator 231b and the second switching signal Q2 is transmitted to the AND gate 232b. However, the present invention is not limited thereto, The phase difference can be detected even if the resonant voltage Vir is transmitted to the negative input terminal of the comparator 231b and the first switching signal Q1 is transmitted to the end gate 232b.

8 is a flow chart illustrating a protection operation in a power supply device including the LLC converter shown in Fig.

8, the power supply 200 may sense the resonant inductor current Ir of the LLC converter 210. (S800) The sensing of the resonant inductor current Ir is performed by sensing the current And the current sensing unit 220 can output the resonance voltage Vir corresponding to the sensed resonance inductor current Ir.

The power supply 200 can determine the phase difference between the resonant inductor current Ir and the first switching signal Q1 or the second switching signal Q2. (S810) The resonant voltage Vir is determined by the resonant inductor current (Ir) and can have the same phase as the resonant inductor current (Ir). The phase difference can be determined by comparing the time point at which the resonance voltage Vir corresponding to the magnitude of the resonance inductor current Ir becomes a predetermined value and the turning-on point of the first switching signal or the second switching signal. Also, the phase difference can be determined by comparing the time point at which the resonance voltage Vir changes from a negative value to a positive value and the turn-on time of the first switching signal Q1, and when the resonance voltage Vir is positive The phase difference can be determined by comparing the time point at which the second switching signal Q2 is changed to the negative value and the time point at which the second switching signal Q2 is turned on.

When the phase difference between the resonant inductor current Ir and the first switching signal Q1 or the second switching signal Q2 is less than a preset value, the power supply 200 outputs a protection signal to operate the LLC converter 210 (S820). The protection circuit 230 can output the protection signal. The determination of the phase difference can be made using the pulse width corresponding to the magnitude or phase difference of the voltage corresponding to the phase difference in the protection circuit 230.

The functions of the various elements shown in the drawings of the present invention may be provided through use of dedicated hardware as well as hardware capable of executing software in association with appropriate software. When provided by a processor, such functionality may be provided by a single dedicated processor, a single shared processor, or a plurality of individual processors, some of which may be shared.

In the claims hereof, the elements depicted as means for performing a particular function encompass any way of performing a particular function, such elements being intended to encompass a combination of circuit elements that perform a particular function, Microcode, etc., coupled with suitable circuitry to perform the software for the computer system 100. The computer system 100 may include any type of software, including firmware, microcode, etc.,

Reference throughout this specification to " one embodiment ", etc. of the principles of the invention, and the like, as well as various modifications of such expression, are intended to be within the spirit and scope of the appended claims, it means.

It will be understood that the term " connected " or " connecting ", and the like, as used in the present specification are intended to include either direct connection with other components or indirect connection with other components. Also, the singular forms in this specification include plural forms unless the context clearly dictates otherwise. Also, components, steps, operations, and elements referred to in the specification as " comprises " or " comprising " refer to the presence or addition of one or more other components, steps, operations, elements, and / or devices.

200: power supply unit 210: LLC converter
220: current sensing unit 230: protection circuit
Q1: first switching signal Q2: second switching signal
Ir: resonant inductor current

Claims (13)

An LLC converter for outputting an input voltage with a predetermined output voltage by a first switching signal and a second switching signal;
A current sensing unit for sensing a resonant inductor current flowing in the LLC converter; And
And a protection circuit for outputting a protection signal for stopping the operation of the LLC converter in accordance with the resonance inductor current and the phase difference between the first switching signal and the second switching signal. The method according to claim 1,
The protection circuit
Wherein the phase difference is determined by comparing a time point when the first voltage corresponding to the magnitude of the resonance inductor current sensed by the current sensing unit reaches a predetermined value and a time point when the first switching signal or the second switching signal is turned on, . 3. The method of claim 2,
Wherein the protection circuit outputs the protection signal when the phase difference is less than a predetermined value. The method of claim 3,
Wherein the protection circuit generates a pulse corresponding to the phase difference and determines that the phase difference is equal to or less than the preset value when the second voltage corresponding to the pulse is lower than a predetermined voltage. 5. The method of claim 4,
The protection circuit comprising:
A first comparator comparing the magnitude of the resonant inductor current with a first reference voltage to output a high signal when the magnitude of the resonant inductor current is less than the first reference voltage, A phase detector for calculating the first switching signal or the second switching signal to generate the pulse;
The second voltage corresponding to the pulse
And a second comparator for comparing the output of the level converter with a second reference voltage and outputting the protection signal when the output of the level converter is smaller than the second reference voltage. The method of claim 3,
Wherein the protection circuit generates a pulse corresponding to the phase difference and determines that the phase difference is less than or equal to the preset value if the pulse width is shorter than a predetermined pulse width. The method according to claim 6,
The protection circuit comprising:
A first comparator comparing the magnitude of the resonant inductor current with a first reference voltage to output a high signal when the magnitude of the resonant inductor current is less than the first reference voltage, A phase detector for calculating the first switching signal or the second switching signal to generate the pulse;
And a duty detector for detecting the width of the pulse and outputting the protection signal when the width of the pulse is less than a predetermined value. 3. The method of claim 2,
The protection circuit comprising:
A time point at which the first voltage changes from a negative value to a positive value based on the predetermined value and a turning-on time of the first switching signal are compared, and a time point when the first voltage changes from positive to negative based on the predetermined value And comparing the turn-on time of the second switching signal. The method according to claim 1,
Wherein the LLC converter further includes a controller for outputting the first switching signal and the second switching signal, and the protection signal is transmitted to the controller to stop the controller. The method according to claim 1,
Wherein the LLC converter further comprises a control unit for outputting the first switching signal and the second switching signal, and the protection signal prevents the first switching signal and the second switching signal from being outputted from the control unit. And a LLC converter that receives the first switching signal and the second switching signal to generate a predetermined voltage, the method comprising:
Sensing a resonant inductor current of the LLC converter;
Determining a phase difference between the resonant inductor current and the first switching signal or the second switching signal; And
And outputting a protection signal to stop the operation of the LLC converter if the phase difference is less than a preset value. 12. The method of claim 11,
Wherein when the resonance voltage corresponding to the magnitude of the resonance inductor current changes from negative to positive, the phase difference is a phase difference between the resonance inductor current and the first switching signal, and when the resonance voltage has a positive value, Wherein the phase difference is the phase difference between the resonant inductor current and the second switching signal. 12. The method of claim 11,
Wherein the step of determining the phase difference is performed by using a magnitude of a voltage corresponding to the phase difference or a pulse width corresponding to the phase difference.

Images