JP2019080415A - Psr current control system with llc structure - Google Patents

Abstract

To provide a PSR current control system with a LLC structure that acquires a transformer current signal at a primary side and calculates an output current to stably control it.SOLUTION: A PSR current control system with a LLC structure comprises: a voltage polarity conversion circuit; a current signal sampling circuit; a current crossover detection circuit; a zero current detection circuit; and a current integration circuit. After the voltage polarity conversion circuit acquires a voltage signal from a primary side of a LLC transformer to output a positive voltage signal, the current integration circuit acquires respective current input signal output from the current signal sampling circuit, zero point current point output from the current crossover detection circuit, and zero current state output by the zero current detection circuit. Based on the zero point current point and a zero current state, a minimum current level of the current input signal is increased up to a zero point current and a current integration waveform is generated. After the integration, an output current is generated and the LLC transformer acquires an output current for controlling an output state of a secondary side directly from the primary side.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a PSR current control system in an LLC structure, and in particular, achieves a PSR current control system in an LLC structure that controls stably by acquiring a transformer current signal on the primary side and estimating an output current. It is a thing.

  In recent years, the market for consumer electronic products and LED drive circuits is constantly growing, and power supply converters are required to be miniaturized and to save power. The LLC structure is already used in large quantities for high efficiency voltage conversion systems, such as PCs, server power supplies, lighting or network communication power supplies. In LLC control, which is often seen, feedback is adjusted on the conventional secondary side, and constant voltage and constant current control is achieved by a set of photocouplers and a comparator (Error Amplifier) on the secondary side. The main application in the secondary circuit is to transmit the signal on the secondary side to the primary side, and when the feedback circuit adjusts the duty ratio of the pulse signal with this signal, the output load fluctuates. However, the power supply is still able to provide stable current and voltage for use in the output load, and there is a negative change in the operating frequency of the LLC as the load changes. Emerging, transformer current can operate in three modes as follows: When the operating frequency is lower than the resonant frequency, the current operating mode of the transformer shifts to discontinuous connection mode (DCM) When the operating frequency is equal to the resonant frequency, the current operating mode of the transformer shifts to the critical mode; when the operating frequency is higher than the resonant frequency, the current operating mode of the transformer is the continuous connection mode To migrate to de (CCM). The conventional control method increases the number of parts on the secondary side, PCB space and cost, and power loss occurs in the detection circuit on the secondary side, which affects standby power consumption. Therefore, many persons skilled in the art have developed towards PSR (Primary-Side Regulation).

  PSR can achieve constant current and constant voltage control by controlling the output load condition through the primary side, without requiring a feedback circuit on the secondary side. This control method is to stabilize the output load condition by controlling the duty ratio of the pulse signal by detecting the voltage signal on the additional winding of the primary side transformer.

The most frequently used PSR control structure is called Flyback, but Flyback must operate in the critical mode or discontinuous connection mode, and once enters the continuous connection mode (COM). , Flyback's PSR control will not work. However, in the LLC structure, the output gain is changed by changing the frequency. Therefore, it is not possible to limit which mode the LLC operation is in.
In view of the above-mentioned disadvantages of the prior art, the inventor finally came up with the present invention for the path of research improvement to the above-mentioned disadvantages.

  The main object of the present invention is to achieve a PSR current control system with LLC structure to obtain transformer current signal on the primary side, calculate output current and control it stably.

The technical means adopted by the present invention in order to achieve the above objects and effects is
A voltage polarity conversion circuit electrically connected to a primary side of an LLC transformer provided in advance and converting a negative voltage in a voltage signal into a positive voltage and outputting a positive voltage signal;
A current signal sampling circuit electrically connected to the voltage polarity conversion circuit and receiving a positive voltage signal to acquire a current input signal;
A current crossover detection circuit electrically connected to the voltage polarity conversion circuit and receiving a positive voltage signal and calculating a zero point current point;
A zero current sensing circuit electrically connected to the primary side of the LLC transformer for sensing a zero current condition;
The current signal sampling circuit, the current crossover detection circuit and the zero current detection circuit are respectively electrically connected to receive the current input signal, the zero point current point and the zero current state, and the zero point current point and the zero current state And raising the lowest current level of the current input signal to the zero point current point to generate a current integration waveform and generate an output current after integration, and
As a result, after the voltage polarity conversion circuit acquires a voltage signal from the primary side of the LLC transformer and outputs a positive voltage signal, the current integration circuit detects the current input signal output from the current signal sampling circuit, current crossover detection The zero point current point output by the circuit and the zero current state output by the zero current detection circuit are acquired respectively, and the lowest current level of the current input signal is increased to the zero point current based on the zero point current point and the zero current state The current integration waveform is generated and the output current is generated after integration, and the LLC transformer obtains the output current for controlling the output state of the secondary side directly from the primary side.

  According to the above structure, the zero current detection circuit is electrically connected to a zero potential node provided in advance in the LLC transformer.

  According to the above structure, the current integrating circuit is electrically connected to the LED driving circuit provided in advance.

  The above objects, effects, and features of the present invention will be described as follows based on the respective drawings so as to be more specifically understood.

It is a circuit block diagram of the example of the present invention. It is the schematic of the partial circuit block in FIG. It is an operation | movement wave form diagram in continuous connection mode of this invention. FIG. 5 is a schematic diagram of waveform decomposition in FIG. 3; It is an operation | movement wave form diagram in discontinuous connection mode of this invention. It is an operation | movement wave form diagram in the critical mode of this invention.

  Please refer to FIG. 1 and FIG. It can be seen that the structure of the invention mainly comprises:

A voltage polarity conversion circuit 2 electrically connected to a primary side of an LLC transformer 1 provided in advance and converting a negative voltage in a voltage signal into a positive voltage and outputting a positive voltage signal;
A current signal sampling circuit 3 electrically connected to the voltage polarity conversion circuit 2 and receiving a positive voltage signal to acquire a current input signal;
A current crossover detection circuit 4 electrically connected to the voltage polarity conversion circuit 2 and receiving a positive voltage signal and calculating a zero point current point;
A zero current detection circuit electrically connected to the primary side of the LLC transformer 1 to detect a zero current state, that is, electrically connected to a zero potential node ZCD previously provided to the LLC transformer. 5 and
The current signal sampling circuit 3, the current crossover detection circuit 4 and the zero current detection circuit 5 are electrically connected to each other, receive the current input signal, the zero point current point and the zero current state, Based on the zero current state, the lowest current level of the current input signal is raised to the zero point current point to generate a current integration waveform and generate an output current after integration, and an output current is provided in advance for the LED drive circuit And a current integration circuit 6 for transmitting to 7,
Thus, after the voltage polarity conversion circuit 2 acquires a voltage signal from the primary side of the LLC transformer 1 and outputs a positive voltage signal, the current integration circuit 6 outputs the current input signal output from the current signal sampling circuit 3; The zero current point output from the current crossover detection circuit 4 and the zero current state output from the zero current detection circuit 5 are obtained, and the minimum current level of the current input signal is obtained based on the zero current point and the zero current state. The current integration waveform is generated and the output current is generated after integration, and the LLC transformer 1 obtains the output current for controlling the output state of the secondary side directly from the primary side. Control the LED drive circuit 7;

Please refer to FIG. 3 to FIG. 6 simultaneously. The control waveform of control signal A is divided into positive period S1 and negative period S2 based on positive and negative half cycles, and sampling current ISH corresponds to control signal A, and the actual current waveform ir represents, for example, a current waveform diagram as shown by an oscilloscope; the excitation current iM is derived from that generated during operation of the LLC transformer 1 and is for calculating and acquiring the output current IOUT; stable excitation current The iM is temporarily cut off in one stable output state when the LLC transformer 1 converts the control signal A. And ID1 and ID2 are the result acquired by the last operation, and when the present invention starts operation,
Time point t0 to t1: Since the sampling current ISH is a negative voltage, the voltage polarity conversion circuit 2 converts the negative voltage to a positive voltage;
Time t1 to t2: obtaining a sampling current ISH converted to a positive voltage;
Time point t2 to t4: Zero current output is detected at the zero current detection point ZCD of the zero current detection circuit 5, and the sampling current ISH is fixed to the current value at the time of zero current generation;
Time t3 to t4: The current crossover detection circuit 4 detects periodic conversion of the control signal A and converts it from low potential to high potential, but at this time, the output current IOUT is in a positive voltage state; : Simultaneously, the output current shifts from the positive period S1 to the negative period S2, and the voltage polarity conversion circuit 2 converts the sampling current of the negative voltage into a positive voltage;
Time t6 to t0: At this time, after the current integration circuit 6 integrates the current integration waveform at time t0 to t6, the output current IOUT is generated, that is, the current integration circuit 6 has a positive half cycle S1 resonant current ID1, negative Integrate the resonance current ID2 of the half cycle S2 and the LLC transformer 1 obtains the output current for controlling the output state of the secondary side directly from the primary side; one complete control signal A period ends Then, in the subsequent operation, the times t0 to t6 are repeated.

  When comparing the above operation with FIG. 5 and FIG. 6, the waveform decomposer is the same but the difference is the operating mode.

  To summarize the above, the invention patent is filed here under the law, as the PSR current control system in the LLC structure of the present invention is undoubtedly novel and inventive. However, the contents described above are merely descriptions of preferred embodiments of the present invention, and any changes, additions, modifications or equivalent substitutions extending from the technical means and scope of the present invention fall within the claims of the present invention. Fit.

DESCRIPTION OF SYMBOLS 1 LLC transformer 2 Voltage polarity conversion circuit 3 Current signal sampling circuit 4 Current crossover detection circuit 5 Zero current detection circuit 6 Current integration circuit 7 LED drive circuit S1 Positive period S2 Negative period t0, t1, t2, t3, t4 , T5, t6 time point ir Actual current waveform iM Excitation current ID1, ID2 Resonant current IM Stable excitation current ISH Sampling current IOUT Output current ZCD Zero current detection point A Control signal

The present invention relates to a PSR current control system in an LLC structure, and in particular to calculate the output current of the LLC transformer secondary based on the current signal of the LLC transformer primary and the direction and interruption of the inductor current. in, it is to achieve a PSR current control system in the LLC structure stably controlled.

The main object of the present invention is to stably control the output current on the secondary side of the LLC transformer based on the current signal on the primary side of the LLC transformer and the direction and the intermittent state of the inductor current. The goal is to achieve PSR current control system with LLC structure.

The technical means adopted by the present invention in order to achieve the above objects and effects is
A voltage polarity conversion circuit electrically connected to a primary side of an LLC transformer provided in advance and converting a negative voltage in a voltage signal into a positive voltage and outputting a positive voltage signal;
A current signal sampling circuit electrically connected to the voltage polarity conversion circuit and receiving a positive voltage signal to acquire a current input signal;
A current direction crossover detection circuit electrically connected to the voltage polarity conversion circuit and receiving a positive voltage signal and calculating a zero point current point;
A zero current sensing circuit electrically connected to the primary side of the LLC transformer for sensing a zero current condition;
The current signal sampling circuit, the current direction crossover detection circuit and the zero current detection circuit are electrically connected to each other, receive the current input signal, the zero point current point and the zero current state, and the zero point current point and the zero current A current integration circuit that raises the lowest current level of the current input signal to the zero point current point based on the state to generate a current integration waveform and generates an output current after integration;
Thus, the voltage polarity conversion circuit causes the current to flow from the primary side of the LLC transformer.
The zero current detection circuit can determine the positive and negative directions of the current through the detection of the zero point current point, since the current contains different phases of positive and negative, and the current can include the voltage signal generated by passing through. The current sensing circuit acquires the time point at which this positive and negative convert, and the voltage polarity conversion circuit raises the voltage input signal acquired at this time above the voltage zero point, ie taking the absolute value of this voltage, and The output is a positive voltage signal, and the current signal sampling circuit detects an intermittent state of the inductor current reflected from the secondary side to the primary side of the LLC transformer, and the current integration circuit generates a current signal sampling circuit. outputted by the current input signal, current direction crossover detection circuit zero current point output, respectively obtains zero current state in which the output is zero current detection circuit, zero current point and zero conductivity Based on the state, by increasing the minimum current level of the current input signal to the zero point current, to generate a current integral waveform, the current integrator circuit within the time the inductor current of the secondary side of the LLC transformer exists The integration is performed on the current integration waveform, and after integration, the output current is generated, and the LLC transformer obtains the output current for controlling the output state of the secondary side directly from the primary side, and the primary and secondary coils are Control the LED drive circuit through ratio conversion.

A voltage polarity conversion circuit 2 electrically connected to a primary side of an LLC transformer 1 provided in advance and converting a negative voltage in a voltage signal into a positive voltage and outputting a positive voltage signal;
A current signal sampling circuit 3 electrically connected to the voltage polarity conversion circuit 2 and receiving a positive voltage signal to acquire a current input signal;
A current alternating current crossover detection circuit 4 electrically connected to the voltage polarity conversion circuit 2 and receiving a positive voltage signal and calculating a zero point current point;
A zero current detection circuit electrically connected to the primary side of the LLC transformer 1 to detect a zero current state, that is, electrically connected to a zero potential node ZCD previously provided to the LLC transformer. 5 and
The current signal sampling circuit 3, the current direction crossover detection circuit 4, and the zero current detection circuit 5 are electrically connected to each other, receive the current input signal, the zero point current point, and the zero current state, The lowest current level of the current input signal is raised to the zero point current point based on the zero and current states to generate a current integration waveform and generate an output current after integration, and output current is pre-provided LED drive And a current integration circuit 6 for transmission to the circuit 7;
As a result, the voltage polarity conversion circuit 2 acquires a voltage signal generated from the primary side of the LLC transformer 1 when the current passes through the electrical resistance, and the current includes different positive and negative phases, so the zero current detection circuit 5 can determine the positive and negative directions of the current through detection of the zero point current point, and the zero current detection circuit 5 obtains a time point at which this positive and negative are converted, and the voltage polarity conversion circuit 2 The voltage input signal obtained at the point is raised above the voltage zero point, ie taking the absolute value of this voltage, and its output is a positive voltage signal, through the current signal sampling circuit 3 the secondary side of the LLC transformer 1 detecting the engaged state of the inductor current to be reflected to the primary side from a current integrating circuit 6, the current input signal is a current signal sampling circuit 3 and the output, the current direction crossover detection circuit 4 outputs Acquire the zero current state output from the zero point current point and the zero current detection circuit 5, respectively, and raise the lowest current level of the current input signal to the zero point current based on the zero point current point and the zero current state, While generating the current integration waveform , the current integration circuit 6 integrates the current integration waveform in the time when the inductor current on the secondary side of the LLC transformer is present, and generates an output current after integration , the LLC transformer 1 obtains an output current for controlling an output state on the secondary side directly from the primary side, and controls the LED drive circuit 7 through conversion of the ratio between the primary and secondary coils.

Please refer to FIG. 3 to FIG. 6 simultaneously. The control waveform of control signal A is divided into positive period S1 and negative period S2 based on positive and negative half cycles, and sampling current ISH corresponds to control signal A, and the actual current waveform ir represents, for example, a current waveform diagram as shown by an oscilloscope; the excitation current iM is derived from that generated during operation of the LLC transformer 1 and is for calculating and acquiring the output current IOUT; stable excitation current The iM is temporarily cut off in one stable output state when the LLC transformer 1 converts the control signal A. And ID1 and ID2 are the result acquired by calculation at the end , and when the present invention starts operation,
Time point t0 to t1: Since the sampling current ISH is a negative voltage, the voltage polarity conversion circuit 2 converts the negative voltage to a positive voltage;
Time t1 to t2: obtaining a sampling current ISH converted to a positive voltage;
Time point t2 to t4: Zero current output is detected at the zero current detection point ZCD of the zero current detection circuit 5, and the sampling current ISH is fixed to the current value at the time of zero current generation;
Time t3 to t4: The current direction crossover detection circuit 4 detects periodic conversion of the control signal A and converts it from low potential to high potential, but at this time, the output current IOUT is in a positive voltage state; t5: Simultaneously, the output current shifts from the positive period S1 to the negative period S2, and the voltage polarity conversion circuit 2 converts the sampling current of the negative voltage into a positive voltage;
Time t6 to t0: At this time, after the current integration circuit 6 integrates the current integration waveform at time t0 to t6, the output current IOUT is generated, that is, the current integration circuit 6 has a positive half cycle S1 resonant current ID1, negative Integrate the resonance current ID2 of the half cycle S2 and the LLC transformer 1 obtains the output current for controlling the output state of the secondary side directly from the primary side; one complete control signal A period ends Then, in the subsequent operation, the times t0 to t6 are repeated.

1 LLC Transformer 2 Voltage Polarity Conversion Circuit 3 Current Signal Sampling Circuit 4 Current Direction Crossover Detection Circuit 5 Zero Current Detection Circuit 6 Current Integration Circuit 7 LED Drive Circuit S1 Positive Period S2 Negative Period t0, t1, t2, t3, t4, t5, t6 time point ir Actual current waveform iM Excitation current ID1, ID2 Resonant current IM Stable excitation current ISH Sampling current IOUT Output current ZCD Zero current detection point A Control signal

Claims (3)

PSR current control system in LLC structure,
A voltage polarity conversion circuit electrically connected to a primary side of an LLC transformer provided in advance and converting a negative voltage in a voltage signal into a positive voltage and outputting a positive voltage signal;
A current signal sampling circuit electrically connected to the voltage polarity conversion circuit and receiving a positive voltage signal to acquire a current input signal;
A current crossover detection circuit electrically connected to the voltage polarity conversion circuit and receiving a positive voltage signal and calculating a zero point current point;
A zero current sensing circuit electrically connected to the primary side of the LLC transformer for sensing a zero current condition;
The current signal sampling circuit, the current crossover detection circuit and the zero current detection circuit are respectively electrically connected to receive the current input signal, the zero point current point and the zero current state, and the zero point current point and the zero current state Based on the lowest current level of the current input signal up to the zero point current point to generate a current integration waveform and generate an output current after integration, the LLC transformer controls the output state of the secondary side And at least a current integration circuit for acquiring an output current directly on the primary side to make the PSR current control system with an LLC structure.   The PSR current control system in an LLC structure according to claim 1, wherein the zero current detection circuit is electrically connected to a zero potential node provided in advance in the LLC transformer.   The PSR current control system with LLC structure according to claim 1, wherein the current integration circuit is electrically connected to a previously provided LED drive circuit.