CN114828326A - Linear drive circuit - Google Patents

Abstract

The invention relates to the technical field of power electronics, and discloses a linear driving circuit, which comprises an energy storage current adjusting unit, a load current adjusting unit and a signal conditioning unit; the load current adjusting unit comprises a second input end and a second control end; the signal conditioning unit respectively inputs a first control signal to the first control end and the second control end; in practical use, the first control signal and the fourth control signal are respectively input to the energy storage current adjusting unit and the load current adjusting unit by adding the signal conditioning unit, so that the charging current of the energy storage unit and the current flowing through the LED load can be simultaneously increased and reduced in the technology of realizing constant current driving, and the light and the color temperature can be adjusted by adjusting the current of the LED load.

Description

Linear drive circuit

Technical Field

The invention relates to the technical field of power electronics, in particular to a linear driving circuit.

Background

The existing linear driving circuit for driving the single-path LED load mainly comprises a rectifying unit, an energy storage unit, a charging current adjusting unit and a load current adjusting unit, wherein the rectifying unit charges the energy storage unit periodically, the output voltages of the energy storage unit and the rectifying unit alternately supply power to the load, the charging current adjusting unit adjusts the charging current of the energy storage unit during charging, and the load current adjusting unit adjusts the current flowing through the load. Although the conventional linear driving circuit realizes the constant current driving of the LED load, the conventional linear driving circuit cannot meet the requirements of dimming and color temperature adjustment for some application occasions requiring dimming and color temperature adjustment.

Disclosure of Invention

In view of the shortcomings of the background art, the present invention provides a linear driving circuit, and aims to solve the technical problem that the existing linear driving circuit cannot meet the requirements of dimming and color temperature regulation of an LED load.

In order to solve the technical problems, the invention provides the following technical scheme: the linear driving circuit comprises an energy storage current regulating unit, a load current regulating unit, a signal conditioning unit, a voltage detection unit, an instantaneous voltage compensation unit and a periodic voltage compensation unit;

the energy storage current regulating unit comprises a first input end, the load current regulating unit comprises a second input end, and the signal conditioning unit inputs a first control signal to the energy storage current regulating unit and a fourth control signal to the load current regulating unit;

the instantaneous voltage compensation unit comprises a fourth input end and a fourth output end, the periodic voltage compensation unit comprises a fifth input end and a fifth output end, and the voltage detection unit comprises a detection input end and a detection output end; the detection output end is respectively electrically connected with the fourth input end and the fifth input end, voltage detection signals are input to the fourth input end and the fifth input end, the fourth output end of the instantaneous voltage compensation unit outputs a second control signal, the fifth output end of the periodic voltage compensation unit outputs a third control signal, and the second control signal and the third control signal are input to the energy storage current regulation unit;

the energy storage current adjusting unit reduces the current flowing through the first input end when the input control signal is increased, and increases the current flowing through the first input end when the input control signal is decreased; the load current adjusting unit decreases a current flowing through the second input terminal when the fourth control signal increases, and increases a current flowing through the second input terminal when the fourth control signal decreases.

In one embodiment, the signal conditioning unit includes a third input terminal and two third output terminals, the third input terminal is configured to input a conditioning signal, one third output terminal of the signal conditioning unit outputs a first control signal, and the other third output terminal of the signal conditioning unit outputs a fourth control signal; when the conditioning signal is a PWM signal, the first control signal and the fourth control signal are respectively in positive correlation with a duty cycle of the conditioning signal, or the first control signal and the fourth control signal are respectively in negative correlation with a duty cycle of the conditioning signal; when the conditioning signal is a direct current signal, the first control signal and the fourth control signal are respectively positively correlated with the voltage of the conditioning signal, or the first control signal and the fourth control signal are respectively negatively correlated with the voltage of the conditioning signal.

In a certain embodiment, the present invention includes a signal conditioning unit and at least two load current adjusting units, and the fourth control signals output by the signal conditioning unit are respectively input to the load current adjusting units.

In a certain embodiment, the present invention includes M signal conditioning units and M load current adjusting units, where M is a positive integer and greater than or equal to 2, first control signals output by the M signal conditioning units are all input to the energy storage current adjusting unit, and a fourth control signal output by one signal conditioning unit is input to one load current adjusting unit.

In one embodiment, the second control signal is positively correlated with the voltage detection signal;

the periodic voltage compensation unit calculates a voltage detection signal within time T and outputs a third control signal based on the calculation result; the periodic voltage compensation unit increases the third control signal when the calculation result is greater than a determination threshold value, decreases the third control signal when the calculation result is less than the determination threshold value, or increases the third control signal when the calculation result is less than the determination threshold value, and decreases the third control signal when the calculation result is greater than the determination threshold value.

In a certain embodiment, the energy storage current adjusting unit includes a first operational amplifier circuit and a first control switch, an output end of the first operational amplifier circuit is electrically connected to a control end of the first control switch, an output end of the first control switch is electrically connected to a feedback end of the first operational amplifier circuit, or an output end of the first control switch is electrically connected to a feedback end of the first operational amplifier circuit through a resistor;

the first control signal, the second control signal and the third control signal are all input to a negative input end of the first operational amplifier circuit, and a first reference voltage is input to a positive input end of the first operational amplifier circuit; or the first control signal and the second control signal are both input to the negative input end of the first operational amplifier circuit, the third control signal is input to the first input end of the subtracter, the first reference voltage is input to the second input end of the subtracter, and the output end of the subtracter is electrically connected with the positive input end of the first operational amplifier circuit.

In one embodiment, the load current adjusting unit includes a second operational amplifier circuit and a second control switch, an output end of the second operational amplifier circuit is electrically connected to a control end of the second control switch, an output end of the second control switch is electrically connected to a feedback end of the second operational amplifier circuit, or an output end of the second control switch is electrically connected to a feedback end of the second operational amplifier circuit through a resistor;

the fourth control signal is input to a negative input end of the second operational amplifier circuit, and a second reference voltage is input to a positive input end of the second operational amplifier circuit; or the second reference voltage and the fourth control signal are both input to an input end of the second subtractor, and an output end of the second subtractor is electrically connected with a positive input end of the second operational amplifier circuit.

In one embodiment, the third control signal is input to a negative input terminal of the second operational amplifier circuit; or the third control signal is input to an input terminal of the second subtractor.

In a certain embodiment, the invention further comprises a rectifying unit and an energy storage unit, wherein a direct-current voltage output end of the rectifying unit is electrically connected with one end of the energy storage unit, and the other end of the energy storage unit is electrically connected with a first input end of the energy storage current regulating unit; and the detection input end of the voltage detection unit is electrically connected with at least one electrical node among one end of the energy storage unit, the first input end of the energy storage current regulation unit and the second input end of the load current regulation unit.

In addition, the invention also provides a second linear driving circuit which comprises an energy storage current regulating unit, a load current regulating unit, a conditioning unit, a voltage detecting unit, an instantaneous voltage compensating unit and a periodic voltage compensating unit;

the energy storage current regulating unit comprises a first input end, and the load current regulating unit comprises a second input end; the instantaneous voltage compensation unit comprises a fourth input end and a fourth output end, the periodic voltage compensation unit comprises a fifth input end and a fifth output end, and the voltage detection unit comprises a detection input end and a detection output end; the detection output end is respectively and electrically connected with the fourth input end, the fifth input end and the signal conditioning unit, voltage detection signals are respectively input to the fourth input end, the fifth input end and the signal conditioning unit, the fourth output end of the instantaneous voltage compensation unit outputs a second control signal, the fifth output end of the periodic voltage compensation unit outputs a third control signal, the conditioning unit outputs a first control signal and a fourth control signal when the voltage detection signal is greater than a judgment threshold value, the first control signal and the fourth control signal are positively correlated with the voltage detection signal, and the first control signal, the second control signal and the third control signal are all input to the energy storage current conditioning unit; the fourth control signal is input to the load current adjusting unit;

the energy storage current adjusting unit reduces the current flowing through the first input end when the input control signal is increased, and increases the current flowing through the first input end when the input control signal is decreased; the load current adjusting unit decreases a current flowing through the second input terminal when the fourth control signal increases, and increases a current flowing through the second input terminal when the fourth control signal decreases.

Compared with the prior art, the invention has the beneficial effects that: according to the invention, the signal conditioning unit is additionally arranged to input the first control signal to the energy storage current adjusting unit and the load current adjusting unit, so that the charging current of the energy storage unit and the current flowing through the LED load can be simultaneously increased and reduced in the technology of realizing constant current driving, and the light and color temperature can be adjusted by adjusting the current of the LED load.

Drawings

FIG. 1 is a schematic diagram of a conventional linear driving circuit;

FIG. 2 is a first schematic structural diagram of the present invention in an embodiment;

FIG. 3 is a schematic diagram of a second embodiment of the present invention;

FIG. 4 is a schematic view of a third embodiment of the present invention;

FIG. 5 is a circuit diagram of a voltage detecting unit according to the present invention in an embodiment;

fig. 6 is a schematic diagram of an energy storage current regulating unit of the present invention in an embodiment;

fig. 7 is a schematic diagram of a load current regulating unit of the present invention in an embodiment;

FIG. 8 is a second structural diagram of a load current adjusting unit according to the present invention in an embodiment;

FIG. 9 is a waveform diagram of a voltage detection signal outputted from the voltage detection unit according to the present invention in an embodiment;

fig. 10 is a circuit diagram of a linear driving circuit separately implementing constant power control in an embodiment.

Detailed Description

The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic views illustrating only the basic structure of the present invention in a schematic manner, and thus show only the constitution related to the present invention.

As shown in fig. 2, the linear driving circuit includes an energy storage current adjusting unit 1, a load current adjusting unit 2, and a signal conditioning unit 3;

the energy storage current adjusting unit 1 comprises a first input end, the first input end is electrically connected with one end of a capacitor Cap, the load current adjusting unit 2 comprises a second input end, and the second input end is electrically connected with the cathode of the LED lamp; the signal conditioning unit 3 inputs a first control signal to the energy storage current conditioning unit 1 and inputs a fourth control signal to the load current conditioning unit 2; the energy storage current adjusting unit 1 reduces the current flowing through the first input terminal when the first control signal is increased (reduces the charging current of the capacitor Cap during charging), increases the current flowing through the first input terminal when the first control signal is decreased (increases the charging current of the capacitor Cap during charging), and the load current adjusting unit 2 reduces the current flowing through the second input terminal when the fourth control signal is increased, and increases the current flowing through the second input terminal when the fourth control signal is decreased.

In the linear driving circuit, when the instantaneous voltage of the AC power supply AC is greater than the voltage of the capacitor Cap, the AC power supply AC supplies power to the capacitor Cap and the LED load, and when the instantaneous voltage of the AC power supply AC is less than the voltage of the capacitor Cap, the capacitor Cap supplies power to the LED load.

In addition, the requirement of an input harmonic current test is increased for lighting products such as LEDs with rated power of 5W-P-25W specified in 5 th edition standard IEC 61000-3-2 of the International electrotechnical Commission IEC technical division. Input current waveform requirements: the current reaches at least 5% of the peak value before the conduction angle is 60 degrees, the current reaches the maximum value before the conduction angle is 65 degrees, and the current value cannot be less than 5% at 90 degrees. And the input harmonic current is the sum of the charging current of the capacitor Cap and the current flowing through the LED load, wherein the current flowing through the LED load is constant, and therefore the charging current of the capacitor Cap needs to be controlled.

The linear driving circuit needs to ensure that the current flowing through the LED load is constant, so that when the current of the LED load is increased or reduced, the current of the capacitor Cap during charging needs to be correspondingly adjusted, further, the capacitor Cap does not have the condition of insufficient power supply during supplying power to the LED load and the capacitor Cap does not have the condition of overcharging during charging, the power supply time of the capacitor Cap is longer than the set time, and the LED driving circuit does not meet the standard IEC 61000-3-2 due to light regulation or color temperature. Based on the invention, the signal conditioning unit 3 respectively inputs the first control signal to the first control end and the second control end.

Specifically, the signal conditioning unit 3 includes a third input end and two third output ends, the third input end is configured to input a conditioning signal, one third output end of the signal conditioning unit outputs a first control signal, and the other third output end of the signal conditioning unit outputs a fourth control signal; when the conditioning signal is a PWM signal, the first control signal and the fourth control signal are respectively in positive correlation with the duty ratio of the conditioning signal, or the first control signal and the fourth control signal are respectively in negative correlation with the duty ratio of the conditioning signal; when the conditioning signal is a direct current signal, the first control signal and the fourth control signal are respectively positively correlated with the voltage of the conditioning signal, or the first control signal and the fourth control signal are respectively negatively correlated with the voltage of the conditioning signal.

Taking the first control signal as an example, when the first control signal is positively correlated with the PWM signal, if the duty ratio of the PWM signal is larger, the first control signal is larger, and if the duty ratio of the PWM signal is smaller, the first control signal is smaller; when the first control signal is inversely related to the PWM signal, if the duty ratio of the PWM signal is larger, the first control signal is smaller, and if the duty ratio of the PWM signal is smaller, the first control signal is larger;

when the first control signal is positively correlated with the direct current signal, if the voltage of the direct current signal is larger, the first control signal is larger, and if the voltage of the direct current signal is smaller, the first control signal is smaller; when the first control signal is inversely related to the direct current signal, if the voltage of the direct current signal is larger, the first control signal is smaller, and if the voltage of the direct current signal is smaller, the first control signal is larger;

in addition, referring to fig. 2, in order to make the present invention meet the standard IEC 61000-3-2, the present invention further includes a voltage detection unit 3 and an instantaneous voltage compensation unit 4, wherein the voltage detection unit 3 includes a detection input terminal and a detection output terminal; the instantaneous voltage compensation unit 4 includes a fourth input terminal and a fourth output terminal; the detection output end is electrically connected with the fourth input end, the voltage detection signal is output to the fourth output end, the fourth output end of the instantaneous voltage compensation unit outputs a second control signal, the second control signal is input to the first control end, the second control signal is positively correlated with the voltage detection signal, and the energy storage current adjusting unit 1 reduces the current flowing through the first input end when the second control signal is increased and increases the current flowing through the first input end when the second control signal is reduced.

In fig. 2, the circuit portions in the dashed line frame may be integrated on the same chip, so that when the chips are used in parallel, the parallel connection of the electrical nodes through the line adjusting resistor does not occur, the short circuit can be avoided, and the reliability of the circuit and the system is improved, so that the detection input terminal is electrically connected to at least one electrical node of the first input terminal and the second input terminal. As shown in fig. 5, in an embodiment, the voltage detection unit 3 includes a resistor R2, a resistor R3, and a resistor R4, a capacitor C1 may be connected in parallel across the resistor R4, and the voltage detection unit in fig. 5 includes two detection input terminals electrically connected to the first input terminal and the second input terminal, respectively.

In addition, in practical use, due to errors of the capacitor Cap and the LED load and fluctuation of the input voltage of the power grid, the following three failures may be caused:

failure one: when the capacitor Cap is overcharged in a certain period, the voltage of the capacitor Cap is higher, and the phase of the capacitor Cap is 60 degrees in the next period, the voltage of the capacitor Cap is still larger than the instantaneous value of the input voltage, so that the input current does not meet the specification of the 5 th edition of standard: before the conduction angle is 60 degrees, the current reaches at least 5 percent of the current peak value;

and (5) failure II: when the capacitor Cap is overcharged more seriously, the voltage of the capacitor Cap is still larger than the instantaneous value of the input voltage at the phase of 65 degrees of the next period, so that the input current does not meet the other regulation of the 5 th edition of standard: before 65 ℃, the current is to reach the maximum value;

and (3) failure: if the charging current of the capacitor Cap is insufficient, the capacitor Cap is under-charged, and the voltage of the capacitor Cap is insufficient to maintain the LED load current in the discharging stage of the capacitor Cap to the LED load, namely the voltage of the capacitor Cap in the area near the zero crossing point of the input voltage, thereby causing the stroboscopic phenomenon.

In order to avoid the above failure, referring to fig. 2, in the embodiment, the present invention further includes a periodic voltage compensation unit 5, where the periodic voltage compensation unit 5 includes a fifth input terminal and a fifth output terminal; the voltage detection signal is input to the fifth input terminal, and the periodic voltage compensation unit 5 calculates the voltage detection signal within time T and outputs a third control signal based on the calculation result; the periodic voltage compensation unit 5 increases the third control signal when the calculation result is larger than the determination threshold, decreases the third control signal when the calculation result is smaller than the determination threshold, or increases the third control signal when the calculation result is smaller than the determination threshold, decreases the third control signal when the calculation result is larger than the determination threshold; a third control signal is input to the first control terminal, and the energy storage current adjusting unit 1 reduces the current flowing through the first input terminal when the third control signal increases, and increases the current flowing through the first input terminal when the third control signal decreases.

In actual use, the periodic voltage compensation unit 5 may calculate an average value, a peak value, a valley value, a peak-peak value, an effective value, a quasi-peak value, an overshoot amount, a maximum value, a minimum value, a median value, a differential value, an integrated value, a direct current component, an alternating current component, or an equivalent value of the voltage detection signal over time T.

Among the above parameters, if a certain parameter is positively correlated with the change of the output signal of the voltage detection unit 3, when the calculated value of the output signal is greater than the determination threshold, the periodic voltage compensation unit 5 inputs the third control signal to the energy storage current adjustment unit 1 to reduce the charging current of the capacitor Cap during charging, and when the calculated value of the output signal is less than the determination threshold, the periodic voltage compensation unit 5 inputs the third control signal to the energy storage current adjustment unit 1 to increase the charging current of the capacitor Cap during charging; if the change of a certain parameter and the output signal is inverse proportion, when the calculated value of the output signal is greater than the decision threshold, the periodic voltage compensation unit 5 inputs a third control signal to the energy storage current adjustment unit 1 to increase the charging current of the capacitor Cap during charging, and when the calculated value of the output signal is less than the decision threshold, the periodic voltage compensation unit 5 inputs a third control signal to the energy storage current adjustment unit 1 to reduce the charging current of the capacitor Cap during charging; wherein the charging current of the capacitor Cap may be increased by increasing the third control signal, and the charging current of the capacitor Cap may be increased by decreasing the third control signal.

In some embodiments, the voltage detection unit 3 may also be electrically connected to a Bus point, so that a detection voltage input pin needs to be separately provided on the chip. Fig. 9 shows a waveform diagram of the relevant electrical node in this embodiment, Vin in fig. 9 is a waveform diagram of an ac power supply, Vbus is a voltage waveform diagram of a Bus point, Ccap is a voltage variation waveform diagram of a capacitor Cap, VDET is a waveform diagram of a voltage detection signal output by the voltage detection unit 3, Iin is a current waveform diagram of the capacitor Cap, the ac power supply charges the capacitor Cap when Iin is positive, and the capacitor Cap supplies power to the LED load when Iin is negative. As can be taken from the waveform diagram in fig. 9, the input harmonic current of the present invention satisfies the specifications in the standard IEC 61000-3-2.

In fig. 3, there is only one load current adjusting unit 2, so in actual use, the signal conditioning unit 6 respectively inputs the first control signal to the energy storage current adjusting unit 1 and the load current adjusting unit 2 to adjust the brightness change of the LED load. In practical use, a plurality of load current adjusting units 2 may be provided, a second input end of each load current adjusting unit 2 is electrically connected to one LED load, and the signal conditioning unit 6 is configured to simultaneously input a first control signal to all of the load current adjusting units 2 and the energy storage current adjusting unit 1 to simultaneously adjust the currents of the plurality of LED loads. Specifically, as shown in fig. 3, the linear driving circuit for adjusting color temperature of light in fig. 3 includes two load current adjusting units 2, which can adjust the light intensity of two LED loads at the same time.

In the linear driving circuit for adjusting color temperature of light modulation shown in fig. 4, the linear driving circuit includes two signal conditioning units 6 and two load current adjusting units 2, each load current adjusting unit 2 is connected to one LED load, and the two LED loads can be set as a high temperature string or a low temperature string, so that the color temperature change can be adjusted when the current flowing through the two LED loads is adjusted. Specifically, the first control signals output by the two signal conditioning units 6 are input to the energy storage current adjusting unit 1, the fourth control signal output by one signal conditioning unit 6 is input to one load current adjusting unit 2, and the fourth control signal output by the other signal conditioning unit 6 is input to the energy storage current adjusting unit 1 and the other load current adjusting unit 2, so that the current flowing through the corresponding LED load can be adjusted respectively. In a certain embodiment, more than three load current adjusting units 2 and signal conditioning units 6 may be provided, and the number of load current adjusting units 2 and signal conditioning units 6 is the same.

As shown in fig. 6, the energy storage current adjusting unit 1 includes a first operational amplifier circuit 10 and a first control switch 11, an output end of the first operational amplifier circuit 10 is electrically connected to a control end of the first control switch 11, an output end of the first control switch 11 is electrically connected to a feedback end of the first operational amplifier circuit 10, or an output end of the first control switch 11 is electrically connected to a feedback end of the first operational amplifier circuit 10 through a resistor; in practical use, the first control switch 11 may be an NMOS transistor, and when the first control switch 11 is an NMOS transistor, the first input end of the energy storage current adjusting unit 1 is a drain electrode of the NMOS transistor, and the output end of the energy storage current adjusting unit 1 is a source electrode of the NMOS transistor;

in practical use, for the linear driving circuits of fig. 2 to 4, the first control signal, the second control signal and the third control signal may all be input to the negative input terminal of the first operational amplifier circuit 10, and the positive input terminal of the first operational amplifier circuit inputs the first reference voltage; as the first control signal, the second control signal and the third control signal are all input to the negative input end of the first operational amplifier circuit 10, for a single first control signal, second control signal or third control signal, when a certain control signal is increased, the output voltage of the first operational amplifier circuit 10 is reduced, so that the charging current of the capacitor Cap during charging is reduced, and when a certain signal is reduced, the output voltage of the first operational amplifier circuit 10 is increased, so that the current of the capacitor Cap during charging is increased;

or the first control signal and the second control signal are both input to the negative input end of the first operational amplifier circuit 10, the third control signal is input to the first input end of the subtracter, the second input end of the subtracter inputs the first reference voltage, and the output end of the subtracter is electrically connected with the positive input end of the first operational amplifier circuit 10.

Or the first control signal and the third control signal are both input to the negative input end of the first operational amplifier circuit 10, the second control signal is input to the first input end of the subtracter, the second input end of the subtracter inputs the first reference voltage, and the output end of the subtracter is electrically connected with the positive input end of the first operational amplifier circuit 10;

or the second control signal and the third control signal are both input to the negative input end of the first operational amplifier circuit 10, the first control signal is input to the first input end of the subtracter, the second input end of the subtracter inputs the first reference voltage, and the output end of the subtracter is electrically connected with the positive input end of the first operational amplifier circuit 10;

or the first control signal, the second control signal and the third control signal may all be input to a first input terminal of a subtractor, a first reference voltage is input to a second input terminal of the subtractor, an output terminal of the subtractor is electrically connected to a positive input terminal of the first operational amplifier circuit 10, and a third reference voltage is input to a negative input terminal of the first operational amplifier circuit 10.

When the periodic voltage compensation unit 5 is not provided in the present invention, the first control signal and the second control signal may be both input to the negative input terminal of the first operational amplifier circuit 10, and the positive input terminal of the first operational amplifier circuit inputs the first reference voltage;

or the first control signal may be input to the negative input terminal of the first operational amplifier circuit 10, the second control signal is input to the first input terminal of the subtractor, the second input terminal of the subtractor inputs the first reference voltage, and the output terminal of the subtractor is electrically connected to the positive input terminal of the first operational amplifier circuit 10;

or the second control signal may be input to the negative input terminal of the first operational amplifier circuit 10, the first control signal is input to the first input terminal of the subtractor, the second input terminal of the subtractor inputs the first reference voltage, and the output terminal of the subtractor is electrically connected to the positive input terminal of the first operational amplifier circuit 10;

or the first control signal and the second control signal are both input to the first input end of the subtractor, the second input end of the subtractor inputs the first reference voltage, the output end of the subtractor is electrically connected with the positive input end of the first operational amplifier circuit 10, and the negative input end of the first operational amplifier circuit 10 inputs the third reference voltage.

When the present invention does not have the voltage detection unit 3, the instantaneous voltage compensation unit 4, and the periodic voltage compensation unit 5, the first control signal may be input to the negative input terminal of the first operational amplification circuit 10, and the first reference voltage is input to the positive input terminal of the first operational amplification circuit;

or the first control signal is input to the first input end of the subtractor, the second input end of the subtractor inputs the first reference voltage, the output end of the subtractor is electrically connected with the positive input end of the first operational amplifier circuit 10, and the negative input end of the first operational amplifier circuit 10 inputs the third reference voltage.

As shown in fig. 7, the load current adjusting unit 2 includes a second operational amplifier circuit 20 and a second control switch 21, the second control switch 21 is a MOS transistor M2, a drain of the MOS transistor M2 is a second input terminal of the load current adjusting unit 2, an output terminal of the second operational amplifier circuit 20 is electrically connected to a control terminal of the second control switch 21, an output terminal of the second control switch 21 is electrically connected to a feedback terminal of the second operational amplifier circuit 20, or an output terminal of the second control switch 21 is electrically connected to a feedback terminal of the second operational amplifier circuit 20 through a resistor;

the fourth control signal is input to the negative input terminal of the second operational amplifier circuit 20, and the positive input terminal of the second operational amplifier circuit 20 inputs the second reference voltage;

alternatively, as shown in fig. 8, the second reference voltage and the fourth control signal are both input to an input terminal of a second subtractor, and an output terminal of the second subtractor is electrically connected to the positive input terminal of the second operational amplifier circuit 20.

In one embodiment, the third control signal is input to the negative input terminal of the second operational amplifier circuit 20; or the third control signal is input to the input of the second subtractor. When the periodic voltage compensation unit detects that Vbus is too high, the periodic voltage compensation unit 5 may input a third control signal to the load current adjustment unit 2 to reduce the current of the LED load, so as to implement constant power control.

In addition, the invention also comprises a rectifying unit 7 and an energy storage unit, wherein the energy storage unit is a capacitor Cap, the direct-current voltage output end of the rectifying unit 7 is electrically connected with one end of the energy storage unit, and the other end of the energy storage unit is electrically connected with the first input end of the energy storage current adjusting unit 1; the detection input end of the voltage detection unit 3 is electrically connected with at least one electrical node of one end of the energy storage unit, the first input end of the energy storage current adjusting unit 1 and the second input end of the load current adjusting unit 2.

In summary, the signal conditioning unit 6 is added to input the first control signal to the energy storage current adjusting unit 1 and the load current adjusting unit 2, so that the charging current of the energy storage unit and the current flowing through the LED load can be simultaneously increased and decreased in the technology of realizing constant current driving, and the light and color temperature can be adjusted by adjusting the current of the LED load.

In practical use, when the grid voltage exceeds a certain value, the constant power control of the LED load needs to be realized, as shown in fig. 10, in order to separately realize the constant power control of the linear driving circuit, the invention provides another linear driving circuit, which includes an energy storage current adjusting unit 1, a load current adjusting unit 2, a conditioning unit 9, a voltage detecting unit 3, an instantaneous voltage compensating unit 4, and a periodic voltage compensating unit 5;

the energy storage current regulating unit 1 comprises a first input end, and the load current regulating unit 2 comprises a second input end; the instantaneous voltage compensation unit 4 comprises a fourth input end and a fourth output end, the periodic voltage compensation unit 5 comprises a fifth input end and a fifth output end, and the voltage detection unit 3 comprises a detection input end and a detection output end; the detection output end is respectively electrically connected with the fourth input end, the fifth input end and the conditioning unit 9, voltage detection signals are input to the fourth input end, the fifth input end and the conditioning unit 9, the fourth output end of the instantaneous voltage compensation unit 4 outputs a second control signal, the fifth output end of the periodic voltage compensation unit 5 outputs a third control signal, the conditioning unit 9 outputs a first control signal and a fourth control signal when the voltage detection signals are greater than a judgment threshold value, the first control signal and the fourth control signal are positively correlated with the voltage detection signals, and the first control signal, the second control signal and the third control signal are all input to the energy storage current adjusting unit 1; the fourth control signal is input to the load current adjusting unit 2;

the energy storage current adjusting unit 1 reduces the current flowing through the first input end when the input control signal is increased, and increases the current flowing through the first input end when the input control signal is decreased; the load current adjusting unit 2 reduces the current flowing through the second input terminal when the fourth control signal increases, and increases the current flowing through the second input terminal when the fourth control signal decreases;

the working mechanism of the instantaneous voltage compensation unit 4 and the periodic voltage compensation unit 5 refers to the above content; the decision threshold may be set according to the actual power control requirements.

Similarly, referring to fig. 7, the third control signal and the fourth control signal may be input to a negative input terminal of the second operational amplifier circuit 20, and a positive input terminal of the second operational amplifier circuit 20 may input a fourth reference voltage; or referring to fig. 8, the third control signal and the fourth control signal are input to the second subtractor, the second subtractor also inputs the fifth reference voltage, and the output end of the second subtractor is electrically connected to the positive input end of the second operational amplifier circuit 20; the load current adjusting unit 2 decreases the current flowing through the second control switch 21 when the third control signal increases, and increases the current flowing through the second control switch 21 when the third control signal decreases.

In light of the foregoing, it is to be understood that various changes and modifications may be made by those skilled in the art without departing from the spirit and scope of the invention. The technical scope of the present invention is not limited to the content of the specification, and must be determined according to the scope of the claims.

Claims (10)

1. The linear driving circuit is characterized by comprising an energy storage current regulating unit, a load current regulating unit, a signal conditioning unit, a voltage detecting unit, an instantaneous voltage compensating unit and a periodic voltage compensating unit;

the energy storage current regulating unit comprises a first input end, the load current regulating unit comprises a second input end, and the signal conditioning unit inputs a first control signal to the energy storage current regulating unit and a fourth control signal to the load current regulating unit;

the instantaneous voltage compensation unit comprises a fourth input end and a fourth output end, the periodic voltage compensation unit comprises a fifth input end and a fifth output end, and the voltage detection unit comprises a detection input end and a detection output end; the detection output end is respectively electrically connected with the fourth input end and the fifth input end, voltage detection signals are input to the fourth input end and the fifth input end, the fourth output end of the instantaneous voltage compensation unit outputs a second control signal, the fifth output end of the periodic voltage compensation unit outputs a third control signal, and the second control signal and the third control signal are input to the energy storage current regulation unit;

the energy storage current adjusting unit reduces the current flowing through the first input end when the input control signal is increased, and increases the current flowing through the first input end when the input control signal is decreased; the load current adjusting unit decreases a current flowing through the second input terminal when the fourth control signal increases, and increases a current flowing through the second input terminal when the fourth control signal decreases.

2. The linear driving circuit according to claim 1, wherein the signal conditioning unit comprises a third input terminal and two third output terminals, the third input terminal is configured to input a conditioning signal, one third output terminal of the signal conditioning unit outputs a first control signal, and the other third output terminal of the signal conditioning unit outputs a fourth control signal; when the conditioning signal is a PWM signal, the first control signal and the fourth control signal are respectively in positive correlation with a duty cycle of the conditioning signal, or the first control signal and the fourth control signal are respectively in negative correlation with a duty cycle of the conditioning signal; when the conditioning signal is a direct current signal, the first control signal and the fourth control signal are respectively positively correlated with the voltage of the conditioning signal, or the first control signal and the fourth control signal are respectively negatively correlated with the voltage of the conditioning signal.

3. The linear driving circuit according to claim 1, comprising a signal conditioning unit and at least two load current adjusting units, wherein the fourth control signals output by the signal conditioning unit are respectively input to the load current adjusting units.

4. The linear driving circuit according to claim 1, comprising M signal conditioning units and M load current adjusting units, wherein M is a positive integer and greater than or equal to 2, first control signals output by the M signal conditioning units are all input to the energy storage current adjusting unit, and a fourth control signal output by one signal conditioning unit is input to one load current adjusting unit.

5. The linear driving circuit according to claim 1, wherein the second control signal is positively correlated with the voltage detection signal;

the periodic voltage compensation unit calculates a voltage detection signal within time T and outputs a third control signal based on the calculation result; the periodic voltage compensation unit increases the third control signal when the calculation result is greater than a determination threshold value, decreases the third control signal when the calculation result is less than the determination threshold value, or increases the third control signal when the calculation result is less than the determination threshold value, and decreases the third control signal when the calculation result is greater than the determination threshold value.

6. The linear driving circuit according to claim 1, wherein the energy storage current adjusting unit comprises a first operational amplifier circuit and a first control switch, an output terminal of the first operational amplifier circuit is electrically connected to a control terminal of the first control switch, an output terminal of the first control switch is directly electrically connected to a feedback terminal of the first operational amplifier circuit, or an output terminal of the first control switch is electrically connected to the feedback terminal of the first operational amplifier circuit through a resistor;

the first control signal, the second control signal and the third control signal are all input to a negative input end of the first operational amplifier circuit, and a first reference voltage is input to a positive input end of the first operational amplifier circuit; or the first control signal and the second control signal are both input to the negative input end of the first operational amplifier circuit, the third control signal is input to the first input end of the subtracter, the first reference voltage is input to the second input end of the subtracter, and the output end of the subtracter is electrically connected with the positive input end of the first operational amplifier circuit.

7. The linear driving circuit according to claim 1, wherein the load current adjusting unit comprises a second operational amplifier circuit and a second control switch, an output terminal of the second operational amplifier circuit is electrically connected to a control terminal of the second control switch, an output terminal of the second control switch is electrically connected to a feedback terminal of the second operational amplifier circuit, or an output terminal of the second control switch is electrically connected to the feedback terminal of the second operational amplifier circuit through a resistor;

the fourth control signal is input to a negative input end of the second operational amplifier circuit, and a second reference voltage is input to a positive input end of the second operational amplifier circuit; or the second reference voltage and the fourth control signal are both input to an input end of the second subtractor, and an output end of the second subtractor is electrically connected with a positive input end of the second operational amplifier circuit.

8. The linear driving circuit according to claim 7, wherein the third control signal is input to a negative input terminal of the second operational amplification circuit; or the third control signal is input to an input terminal of the second subtractor.

9. The linear driving circuit according to claim 1, further comprising a rectifying unit and an energy storage unit, wherein a dc voltage output end of the rectifying unit is electrically connected to one end of the energy storage unit, and the other end of the energy storage unit is electrically connected to the first input end of the energy storage current adjusting unit; and the detection input end of the voltage detection unit is electrically connected with at least one electrical node among one end of the energy storage unit, the first input end of the energy storage current regulation unit and the second input end of the load current regulation unit.

10. The linear driving circuit is characterized by comprising an energy storage current regulating unit, a load current regulating unit, a conditioning unit, a voltage detecting unit, an instantaneous voltage compensating unit and a periodic voltage compensating unit;

the energy storage current regulating unit comprises a first input end, and the load current regulating unit comprises a second input end; the instantaneous voltage compensation unit comprises a fourth input end and a fourth output end, the periodic voltage compensation unit comprises a fifth input end and a fifth output end, and the voltage detection unit comprises a detection input end and a detection output end; the detection output end is respectively and electrically connected with the fourth input end, the fifth input end and the signal conditioning unit, voltage detection signals are respectively input to the fourth input end, the fifth input end and the signal conditioning unit, the fourth output end of the instantaneous voltage compensation unit outputs a second control signal, the fifth output end of the periodic voltage compensation unit outputs a third control signal, the conditioning unit outputs a first control signal and a fourth control signal when the voltage detection signal is greater than a judgment threshold value, the first control signal and the fourth control signal are positively correlated with the voltage detection signal, and the first control signal, the second control signal and the third control signal are all input to the energy storage current conditioning unit; the fourth control signal is input to the load current adjusting unit;

the energy storage current adjusting unit reduces the current flowing through the first input end when the input control signal is increased, and increases the current flowing through the first input end when the input control signal is decreased; the load current adjusting unit decreases a current flowing through the second input terminal when the fourth control signal increases, and increases a current flowing through the second input terminal when the fourth control signal decreases.

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