Quasi sine wave generator, driving circuit, integrated circuit and lighting device

Abstract

The invention discloses a quasi sine wave generator, a driving circuit, an integrated circuit and a lighting device, and relates to the technical field of circuit design. The technical key points are as follows: the circuit comprises a control circuit and an integrating circuit, and the control circuit controls the integrating circuit to carry out positive integration in at least one part of time of a power supply voltage rising period and carry out negative integration in at least one part of time of a power supply voltage falling period. The invention has the advantage that the circuit waveform is not interfered when the mains supply fluctuates through the structure.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit design, and in particular to a quasi-sine wave generator, a drive circuit, an integrated circuit and a lighting device. Background Art

[0002] When the circuit samples the mains sine waveform to make a current waveform, the mains power grid may be unstable due to the load and various factors, and the circuit current waveform will fluctuate with the mains power. The change in current waveform will cause the LED light to flicker.

[0003] A current solution is to configure the mains current to follow the waveform of the mains voltage in a timely manner, thereby generating a current waveform consistent with the envelope of the mains voltage waveform, thereby forming a higher power factor and lower current harmonics.

[0004] Since the AC voltage is affected by a large number of loads connected to the power grid and various other factors, the voltage waveform is prone to instability, and the corresponding current waveform will also fluctuate with the AC voltage. When this current waveform is used to drive the luminous load LED, the fluctuating current will cause the LED's luminous power to fluctuate, resulting in light flickering. Summary of the invention

[0005] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a quasi-sine wave generator, a drive circuit, an integrated circuit and a lighting device, which have the advantages that the circuit waveform can be undisturbed by the structure when the mains power fluctuates.

[0006] The above object of the present invention is achieved through the following technical solutions:

[0007] A quasi-sine wave generator is used in a circuit for rectifying an alternating current voltage, comprising a control circuit and an integration circuit, wherein the control circuit controls the integration circuit to integrate positively during at least a portion of a rising period of a power supply voltage, and to integrate negatively during at least a portion of a falling period of a power supply voltage;

[0008] The control circuit includes a positive integral start judgment circuit and a negative integral start judgment circuit:

[0009] The positive integration start judgment circuit outputs a positive integration signal in response to the voltage in the rising period of the rectified voltage being greater than the first set threshold VTH1, and controls the integrator to integrate positively;

[0010] The negative integration start judgment circuit outputs a negative integration signal in response to the voltage during the rectified voltage falling period being less than the second set threshold VTH2, and controls the integrator to negatively integrate;

[0011] The control circuit further includes an integration stop judgment circuit, which outputs a stop integration signal in response to the voltage in the rising period of the rectified voltage being greater than a third set threshold VTH3, and controls the integrator to stop integration;

[0012] The integration time constant of the integrator is negatively correlated to the output signal of the integration circuit.

[0013] In a preferred example, the present invention can be further configured as follows: the control circuit further includes a fast integration determination circuit, and the fast integration determination circuit outputs a fast integration signal in response to the rectified voltage being lower than a fourth set threshold VTH4;

[0014] The integration circuit reduces an integration time constant of the integration circuit according to the fast integration signal.

[0015] In a preferred example, the present invention can be further configured as follows: the integration circuit includes an oscillation circuit VCO1, a counting circuit COUNT1 and a digital-to-analog conversion circuit D / A, the oscillation circuit VCO1 generates an output pulse, the counting circuit COUNT1 counts the number of pulses positively, reversely or stops counting according to the positive integration signal, the negative integration signal or the stop integration signal, and the digital-to-analog conversion circuit D / A is configured to convert the output of the counting circuit COUNT1 into an analog signal, and the analog signal is coupled to the output end of the integration circuit.

[0016] In a preferred example, the present invention may be further configured as follows: the integrator further includes a filter circuit FLT1 , and the analog signal is coupled to the output end of the integrator circuit via the filter circuit.

[0017] In a preferred example, the present invention can be further configured as follows: the oscillation circuit increases the frequency of the output pulse according to the fast integration signal, and the frequency of the output pulse of the oscillation circuit is negatively correlated with the analog signal.

[0018] A driving circuit for driving a plurality of groups of LED loads powered by a rectified voltage of an alternating current, comprising a quasi-sine wave generator as claimed in claims 1 to 5, a plurality of field effect transistors, an amplifier circuit EA2 for driving the plurality of field effect transistors, and a sampling resistor RCS for setting the current of the plurality of field effect transistors, wherein the drains of the plurality of field effect transistors are respectively connected to the plurality of groups of LED loads, the amplifier circuit EA2 is coupled to the output of the quasi-sine wave generator, and the plurality of field effect transistors are configured to set the current according to the output signal of the quasi-sine wave generator and the sampling resistor RCS;

[0019] The amplifier circuit EA2 and the plurality of field effect transistors respond to the periodic fluctuation of the rectified voltage, and the plurality of field effect transistors are periodically turned on by the set current in turn.

[0020] An integrated circuit, characterized in that it comprises the quasi-sine wave generator as claimed in claims 1 to 5, a plurality of field effect transistors and an amplifier circuit EA2;

[0021] The integrated circuit includes a plurality of pins, a plurality of power pins connected to the drain of the field effect tube, a setting pin for setting the current of the field effect tube connected to an external sampling resistor RCS, and a common ground.

[0022] A lighting device, characterized in that it comprises the integrated circuit of claim 7, a rectifier for rectifying alternating current, and a plurality of groups of LEDs connected in series in sequence:

[0023] Several groups of LEDs connected in series in sequence have an anode and several cathodes;

[0024] The anode is coupled to the positive electrode of the rectifier, and the cathodes are respectively coupled to the power pins of the integrated circuit in sequence;

[0025] One end of the sampling resistor RCS in the integrated circuit is connected to the setting pin of the integrated circuit, and the other end and the negative electrode of the rectifier are connected to the common ground of the integrated circuit.

[0026] By adopting the above technical solution,

[0027] In summary, the present invention includes at least one of the following beneficial technical effects:

[0028] A quasi-sine wave is generated. Due to the independence of the quasi-sine wave and the mains power, the interference of the power supply to the circuit is eliminated, making the circuit current waveform more stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a preliminary quasi-sine wave schematic diagram;

[0030] Figure 2 It is a schematic diagram of a quasi-sine wave with a fast integration circuit and filter circuit added;

[0031] Figure 3 It is the circuit diagram of the quasi-sine wave generator;

[0032] Figure 4 It is the circuit schematic diagram of the control circuit;

[0033] Figure 5 It is the circuit diagram of the integrator circuit;

[0034] Figure 6 It is the circuit schematic of the integrated circuit;

[0035] Figure 7 It is the circuit schematic diagram of the driving circuit;

[0036] Figure 8 It is a circuit schematic diagram of a lighting device.

[0037] Figure numerals: 1. Positive integration start judgment circuit; 2. Negative integration start judgment circuit; 3. Integration stop judgment circuit; 4. Fast integration judgment circuit. DETAILED DESCRIPTION

[0038] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0039] like Figure 1-5 As shown, a quasi-sine wave generator disclosed in the present invention is applied to a circuit for rectifying an alternating current voltage, and includes a control circuit and an integration circuit. The control circuit controls the integration circuit to integrate positively during at least a portion of the time when the power supply voltage rises, and to integrate negatively during at least a portion of the time when the power supply voltage falls.

[0040] The control circuit includes a positive integral start judgment circuit and a negative integral start judgment circuit:

[0041] Reference Figure 4 The positive integration start judgment circuit has an input terminal and two output terminals, one of which is connected to the cathode of L1 for collecting the rectified voltage, the other is connected to VTH1, and one is connected to the counting circuit. The positive integration start judgment circuit responds to the voltage during the rising period of the rectified voltage being greater than the first set threshold VTH1, and outputs a positive integration signal to control the integrator (counting circuit) to positively integrate (count).

[0042] The negative integration start judgment circuit has two input terminals and one output terminal, one of which is connected to the L3 cathode collection voltage, the other input terminal is connected to VTH2, and one output terminal is connected to the counting circuit. The negative integration start judgment circuit responds to the voltage during the rectified voltage falling period being less than the second set threshold VTH2, and outputs a negative integration signal to control the integrator to negatively integrate.

[0043] The control circuit also includes an integration stop judgment circuit, which has two input terminals and one output terminal, one of which is connected to the L3 cathode collection voltage, the other input terminal is connected to VTH3, and one output terminal is connected to the counting circuit. The integration stop judgment circuit responds to the voltage during the rising period of the rectified voltage being greater than the third set threshold VTH3, and outputs a stop integration signal to control the integrator to stop integration.

[0044] The integration time constant of the integrator is negatively correlated to the output signal of the integration circuit.

[0045] The control circuit also includes a fast integration judgment circuit, which has two input terminals and one output terminal, one of which is connected to the L1 cathode collection voltage, the other input terminal is connected to VTH4, and one output terminal is connected to the oscillation circuit. The fast integration judgment circuit outputs a fast integration signal in response to the rectified voltage being lower than the fourth set threshold VTH4.

[0046] The oscillation circuit reduces the integration time constant of the integration circuit according to the fast integration signal.

[0047] The integration circuit includes an oscillation circuit VCO1, a counting circuit COUNT1, a digital-to-analog conversion circuit D / A and a filtering circuit FLT1, which are connected in series in sequence. The oscillation circuit VCO1 generates an output pulse and transmits it to the counting circuit. The counting circuit COUNT1 counts the number of pulses positively, reversely or stops counting according to the positive integration signal, negative integration signal or stop integration signal. The digital-to-analog conversion circuit D / A is configured to convert the output of the counting circuit COUNT1 into an analog signal, and the analog signal is coupled to the output end of the integration circuit.

[0048] The oscillation circuit increases the frequency of the output pulse according to the fast integration signal, and the frequency of the output pulse of the oscillation circuit is negatively correlated with the analog signal.

[0049] like Figure 6 As shown, an integrated circuit includes a quasi-sine wave generator, a plurality of field effect transistors and an amplifier circuit EA2; the integrated circuit includes a plurality of pins, a plurality of power pins connected to the drain of the field effect transistor, a setting pin for setting the current of the field effect transistor connected to an external sampling resistor RCS, and a common ground connection.

[0050] like Figure 7 As shown, this embodiment is a driving circuit for driving a plurality of groups of LED loads powered by a rectified voltage of an alternating current, comprising a quasi-sine wave generator, a plurality of field effect transistors, an amplifier circuit EA2 for driving the plurality of field effect transistors, and a sampling resistor RCS for setting the current of the plurality of field effect transistors, wherein the drains of the plurality of field effect transistors are respectively connected to the plurality of groups of LED loads, the amplifier circuit EA2 is coupled to the output of the quasi-sine wave generator, and the plurality of field effect transistors are configured to set the current according to the output signal of the quasi-sine wave generator and the sampling resistor RCS; the amplifier circuit EA2 and the plurality of field effect transistors, in response to the periodic fluctuation of the rectified voltage, the plurality of field effect transistors are periodically turned on in turn with the set current.

[0051] like Figure 8 As shown, a lighting device includes an integrated circuit, a rectifier for rectifying alternating current, and a plurality of groups of LEDs connected in series in sequence:

[0052] Several groups of LEDs connected in series have an anode and several cathodes;

[0053] The anode is coupled to the positive electrode of the rectifier, and the cathodes are respectively coupled to the power pins of the integrated circuit in sequence;

[0054] One end of the sampling resistor RCS in the integrated circuit is connected to the setting pin of the integrated circuit, and the other end and the negative electrode of the rectifier are connected to the common ground of the integrated circuit.

[0055] When the lighting device is powered on, the quasi-sine wave generator in the integrated circuit samples the rectified voltage and then generates a quasi-sine wave. The amplifier circuit EA2 in the drive circuit periodically controls the field effect tubes to conduct in turn according to the quasi-sine wave, and the LED lamp beads light up in turn. At this time, when the mains voltage is distorted, the quasi-sine wave generator can generate a quasi-sine wave relatively stably and is not affected by the distortion of the mains voltage. Therefore, by configuring the mains current to follow the waveform of the quasi-sine wave voltage in a timely manner, a current waveform with a consistent envelope of the quasi-sine wave voltage waveform is generated, thereby forming a higher power factor and lower current harmonics while being unaffected by the distortion of the mains voltage.

[0056] The embodiments of this specific implementation method are all preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A quasi-sine wave generator, used in a circuit for rectifying an alternating current voltage, characterized in that: It comprises a control circuit and an integration circuit, wherein the control circuit controls the integration circuit to integrate positively during at least a part of the time when the power supply voltage rises, and to integrate negatively during at least a part of the time when the power supply voltage falls; The control circuit includes a positive integral start judgment circuit and a negative integral start judgment circuit: The positive integration start judgment circuit outputs a positive integration signal in response to the voltage in the rising period of the rectified voltage being greater than the first set threshold VTH1, and controls the integrator to integrate positively; The negative integration start judgment circuit outputs a negative integration signal in response to the voltage during the rectified voltage falling period being less than the second set threshold VTH2, and controls the integrator to negatively integrate; The control circuit further includes an integration stop judgment circuit, which outputs a stop integration signal in response to the voltage in the rising period of the rectified voltage being greater than a third set threshold VTH3, and controls the integrator to stop integration; The integration time constant of the integrator is negatively correlated to the output signal of the integration circuit.

2. A quasi-sine wave generator according to claim 1, characterized in that: The control circuit further comprises a fast integration judgment circuit, which outputs a fast integration signal in response to the rectified voltage being lower than a fourth set threshold VTH4; The integration circuit reduces an integration time constant of the integration circuit according to the fast integration signal.

3. A quasi-sine wave generator according to claim 2, characterized in that: The integration circuit includes an oscillation circuit VCO1, a counting circuit COUNT1 and a digital-to-analog conversion circuit D / A. The oscillation circuit VCO1 generates an output pulse. The counting circuit COUNT1 counts the number of pulses positively, reversely or stops counting according to the positive integration signal, the negative integration signal or the stop integration signal. The digital-to-analog conversion circuit D / A is configured to convert the output of the counting circuit COUNT1 into an analog signal, and the analog signal is coupled to the output end of the integration circuit.

4. A quasi-sine wave generator according to claim 3, characterized in that: The integrator further includes a filter circuit FLT1 , and the analog signal is coupled to an output terminal of the integrator circuit via the filter circuit.

5. The quasi-sine wave generator according to claim 3, characterized in that: The oscillation circuit increases the frequency of the output pulse according to the fast integration signal, and the frequency of the output pulse of the oscillation circuit is negatively correlated with the analog signal.

6. A driving circuit, characterized in that: Used to drive a plurality of groups of LED loads powered by a rectified voltage of an alternating current, comprising a quasi-sine wave generator as claimed in claims 1 to 5, a plurality of field effect transistors, an amplifier circuit EA2 for driving the plurality of field effect transistors, and a sampling resistor RCS for setting the current of the plurality of field effect transistors, wherein the drains of the plurality of field effect transistors are respectively connected to the plurality of groups of LED loads, the amplifier circuit EA2 is coupled to the output of the quasi-sine wave generator, and the plurality of field effect transistors are configured to set the current according to the output signal of the quasi-sine wave generator and the sampling resistor RCS; The amplifier circuit EA2 and the plurality of field effect transistors respond to the periodic fluctuation of the rectified voltage, and the plurality of field effect transistors are periodically turned on by the set current in turn.

7. An integrated circuit, characterized in that: It comprises a quasi-sine wave generator, a plurality of field effect transistors and an amplifier circuit EA2 as claimed in claims 1 to 5; The integrated circuit includes a plurality of pins, a plurality of power pins connected to the drain of the field effect tube, a setting pin for setting the current of the field effect tube connected to an external sampling resistor RCS, and a common ground.

8. A lighting device, characterized in that: The integrated circuit of claim 7, a rectifier for rectifying AC power, and a plurality of groups of LEDs connected in series: A plurality of groups of LEDs connected in series in sequence have an anode and a plurality of cathodes; The anode is coupled to the positive electrode of the rectifier, and the cathodes are respectively coupled to the power pins of the integrated circuit in sequence; One end of the sampling resistor RCS in the integrated circuit is connected to the setting pin of the integrated circuit, and the other end and the negative electrode of the rectifier are connected to the common ground of the integrated circuit.

Images