AC power port harmonic current emission control method and gas discharge electric light source

Abstract

This application provides a method for controlling harmonic current emission from an AC power port and a gas discharge electric light source. The method includes: an MCU control circuit receiving an external trigger signal; the MCU control circuit outputting a flash trigger signal, and delaying the output of a pulse signal with a first duration and a second duration, so that the large capacitor bank charging control circuit controls the PFC control chip and the PFC boost circuit to enter an undervoltage protection state based on the pulse signal, and the PFC boost circuit charges the large capacitor bank in the undervoltage protection state. This method can reduce harmonic current emission.

Description

Technical Field

[0001] The present application relates to the field of circuit design technology, and in particular to a method for controlling harmonic current emission from an AC power port and a gas discharge electric light source. Background Art

[0002] Current harmonics not only affect the quality of grid power supply and waste electricity, but also cause equipment to overheat, increase losses, shorten its service life, and even cause failure or burnout, resulting in significant economic losses. Both domestic and international standards have strict requirements for harmonic current limits.

[0003] The harmonic current of lighting equipment must meet the stricter harmonic current limit of Class C equipment. The harmonic current limit is directly related to the fundamental current and power factor. The specific limit values ​​can be shown in Table 1.

[0004] Table 1

[0005]

[0006] Most product categories can meet standard certification requirements by adding passive or active PFC. However, for products with rapidly fluctuating load power during operation, such as gas discharge electric light sources (typically found in traffic gas strobe fill lights and professional lighting fixtures for stage and studio lighting), the instantaneous power of these products can reach several kilowatts during strobes, with single-shot energy in the tens of joules. Large capacitor banks of several thousand μF draw power from the AC grid within tens of milliseconds to store energy, resulting in severe distortion of the harmonic current waveform. Furthermore, these products spend over 90% of their non-strobe (low power) time during the entire observation period, while the non-strobe power draw is only a few watts. This results in a low average power (typically tens of watts) and a poor power factor throughout the test observation period. Since the harmonic current limits for these products are directly determined by the percentage of the fundamental current, a low fundamental current DC current results in excessively low harmonic current limits. Therefore, simply adding PFC cannot meet harmonic limit requirements. Summary of the Invention

[0007] In view of this, the present application provides a method for controlling harmonic current emission of an AC power port and a gas discharge electric light source.

[0008] Specifically, this application is implemented through the following technical solutions:

[0009] According to a first aspect of an embodiment of the present application, a method for controlling harmonic current emission from an AC power port is provided, which is applied to a gas discharge electric light source, wherein the gas discharge electric light source is provided with a harmonic current optimization circuit, and the harmonic current optimization circuit includes a large capacitor bank charging control circuit; the input end of the large capacitor bank charging control circuit is connected to a microcontroller unit (MCU) control circuit, and the output end is connected to a power factor correction (PFC) control chip. The method includes:

[0010] The MCU control circuit receives an external trigger signal;

[0011] The MCU control circuit outputs a flash trigger signal and delays the first duration to output a pulse signal with a second duration, so that the large capacitor bank charging control circuit controls the PFC control chip and the PFC boost circuit to enter an undervoltage protection state based on the pulse signal, and the PFC boost circuit charges the large capacitor bank in the undervoltage protection state.

[0012] According to a second aspect of an embodiment of the present application, a gas discharge electric light source is provided, comprising: a harmonic current optimization circuit, the harmonic current optimization circuit including a large capacitor bank charging control circuit; the input end of the large capacitor bank charging control circuit is connected to a microcontroller unit (MCU) control circuit, and the output end is connected to a power factor correction (PFC) control chip; wherein:

[0013] The MCU control circuit is configured to output a strobe trigger signal when receiving an external trigger signal, and delay the first duration to output a pulse signal with a second duration;

[0014] The large capacitor bank charging control circuit is used to control the PFC control chip to enter an undervoltage protection state according to the pulse signal;

[0015] The PFC control chip is used to control the PFC boost circuit to be in the undervoltage protection state when in the undervoltage protection state;

[0016] The PFC boost circuit is used to charge the large capacitor bank.

[0017] The technical solution provided by this application can at least bring the following beneficial effects:

[0018] By deploying a large-capacitor group charging control circuit, when the MCU control circuit receives an external trigger signal, it can delay the first duration to output a pulse signal with a second duration, so that the large-capacitor group charging control circuit controls the PFC control chip and the PFC boost circuit to enter the undervoltage protection state based on the pulse signal. The PFC boost circuit charges the large-capacitor group in the undervoltage protection state, thereby reducing harmonic current emission. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a flow chart of a method for controlling harmonic current emission at an AC power port according to an exemplary embodiment of the present application;

[0020] Figure 2 is a schematic diagram of a gas discharge type electric light source shown in an exemplary embodiment of the present application;

[0021] Figure 3A This is a schematic diagram of a typical gas discharge type electric light source in a traditional scheme;

[0022] Figure 3B is a schematic diagram of a typical gas discharge type electric light source with an added harmonic current optimization circuit, shown in an exemplary embodiment of the present application;

[0023] Figure 4 is a schematic diagram of a large capacitor bank charging control circuit shown in an exemplary embodiment of the present application;

[0024] Figure 5 This is an N-channel MOS tube V shown in the exemplary embodiment of the present application. DS Schematic diagram of voltage change trajectory;

[0025] Figure 6 This is a flow chart of a large capacitor bank charging control process shown in an exemplary embodiment of the present application;

[0026] Figure 7A This is a schematic diagram of waveforms measured by an oscilloscope on the AC220 port of a whole device when charging a traffic flashing light without adding a large capacitor bank charging control circuit, as shown in an exemplary embodiment of the present application;

[0027] Figure 7B and Figure 7C The corresponding exemplary embodiment of the present application is shown Figure 7A Schematic diagram of test results of the tester;

[0028] Figure 8 This is a general block diagram of a traffic flashing light with a large capacitor bank charging control circuit added, as shown in an exemplary embodiment of the present application;

[0029] Figure 9A This is a schematic diagram of waveforms measured by an oscilloscope on the AC220 port of the entire device when charging a traffic flashing light with an additional large capacitor bank charging control circuit, as shown in an exemplary embodiment of the present application;

[0030] Figure 9B and Figure 9C The corresponding exemplary embodiment of the present application is shown Figure 7A Schematic diagram of the test results of the tester. DETAILED DESCRIPTION

[0031] Exemplary embodiments will be described in detail herein, with examples illustrated in the accompanying drawings. In the following description, when referring to the drawings, identical numerals in different figures represent identical or similar elements, unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all embodiments consistent with the present application. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present application, as detailed in the appended claims.

[0032] The terms used in this application are for the purpose of describing particular embodiments only and are not intended to limit this application. As used in this application and the appended claims, the singular forms "a," "an," "the," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0033] In order to enable those skilled in the art to better understand the technical solutions provided by the embodiments of the present application, some of the terms involved in the embodiments of the present application are explained below.

[0034] 1. Passive PFC: Passive PFC can be divided into "inductor compensation" and "valley filling circuit" types. Inductor compensation reduces the phase difference between the fundamental current and voltage of the AC input to improve the power factor. Valley filling circuits use a valley filling circuit after the rectifier bridge to increase the conduction angle of the rectifier tube, thereby filling the valley point and transforming the input current from a spike pulse to a near-sine wave.

[0035] 2. Active PFC: A power conversion circuit is added between the rectifier and filter capacitor of the power device itself to correct the input current of the rectifier into a sine wave with the same phase as the grid voltage.

[0036] In order to make the above-mentioned purposes, features and advantages of the embodiments of the present application more obvious and easy to understand, the technical solutions in the embodiments of the present application are further described in detail below with reference to the accompanying drawings.

[0037] See Figure 1 , is a flow chart of a method for controlling harmonic current emission from an AC power port provided in an embodiment of the present application, wherein the method can be applied to a gas discharge electric light source, which is provided with a harmonic current optimization circuit, and the harmonic current optimization circuit includes a large capacitor bank charging control circuit; the input end of the large capacitor bank charging control circuit is connected to an MCU (Microcontroller Unit) control circuit, and the output end is connected to a PFC control chip, such as Figure 1 As shown, the AC power port harmonic current emission control method may include the following steps:

[0038] It should be noted that the AC power port in the embodiment of the present application refers to an AC power port connected to a standard power supply network, such as an AC220V input port or an AC110V input port.

[0039] Step S100: The MCU control circuit receives an external trigger signal.

[0040] In step S110, the MCU control circuit outputs a flash trigger signal and delays the first duration to output a pulse signal with a second duration, so that the large capacitor bank charging control circuit controls the PFC control chip and the PFC boost circuit to enter an undervoltage protection state based on the pulse signal, and the PFC boost circuit charges the large capacitor bank in the undervoltage protection state.

[0041] In the embodiment of the present application, it is taken into consideration that for a gas discharge type electric light source, after it completes the flash, a large capacitor group needs to be charged. Under normal circumstances, even if PFC improvement measures are deployed, when the large capacitor group is charged through the PFC boost circuit, harmonic current exceeding the standard limit will still be generated due to the current distortion at the moment of charging the large capacitor group.

[0042] In order to reduce the harmonic current emission of gas discharge electric light sources, a large capacitor group charging control circuit can be deployed in the gas discharge electric light source. The large capacitor group charging control circuit can slow down the charging rate of the large capacitor group, increase the charging time of the large capacitor group, reduce transient power mutations, and reduce harmonic current emission.

[0043] Accordingly, in an embodiment of the present application, a harmonic current optimization circuit can be provided in a gas discharge electric light source. The harmonic current optimization circuit can include a large capacitor bank charging control circuit; the input end of the large capacitor bank charging control circuit is connected to the MCU control circuit. For example, the input end of the large capacitor bank charging control circuit can be connected to the timing pin (TIM_ETR pin) of the MCU control circuit.

[0044] The output end of the large capacitor group charging control circuit is connected to the PFC control chip. For example, the output end of the large capacitor group charging control circuit can be connected to the BO (Brown Out, undervoltage protection) pin of the PFC control chip.

[0045] Illustratively, the MCU control circuit can receive an external trigger signal, and when receiving the external trigger signal, on the one hand, output a flash trigger signal to trigger the flash light to flash; on the other hand, it can output a pulse signal to enable the large capacitor group charging control circuit to control the PFC control chip and the PFC boost circuit to enter the undervoltage protection state. Then, in the undervoltage protection state, the PFC boost circuit slowly controls the output voltage change and slowly charges the large capacitor group.

[0046] For example, the MCU control circuit can delay the output of a pulse signal with a second width for a first time period through a timing pin; the large capacitor group charging control circuit can control the input voltage of the BO pin of the PFC control chip to be lower than a specified voltage threshold based on the pulse signal, so that the PFC control chip enters the under-voltage protection state, and then controls the PFC boost circuit to enter the under-voltage protection state through the PFC control chip. In the under-voltage protection state, the PFC boost circuit slowly controls the output voltage change and slowly charges the large capacitor group.

[0047] In addition, considering that the flashing process of the flashing lamp usually lasts for a certain period of time, if the PFC boost circuit charges the large capacitor group in the undervoltage protection state during this time, it may affect the normal flashing of the flashing lamp.

[0048] Accordingly, in order to reduce the impact of the charging control of the large capacitor group on the normal flashing of the flashing light, the MCU control circuit can delay for a certain time (referred to as the first time length in this article) and output a pulse signal with a certain width of a certain time length (referred to as the second time length in this article) when receiving an external trigger signal. In this way, it can be ensured that the PFC boost circuit charges the large capacitor group in the undervoltage protection state after the MCU control circuit receives the external trigger signal for the first time length.

[0049] It can be seen that in Figure 1 In the method flow shown, by deploying a large-capacitor group charging control circuit, when the MCU control circuit receives an external trigger signal, it can delay the first duration to output a pulse signal with a second duration, so that the large-capacitor group charging control circuit controls the PFC control chip and the PFC boost circuit to enter the undervoltage protection state based on the pulse signal. The PFC boost circuit charges the large-capacitor group in the undervoltage protection state, thereby reducing harmonic current emission.

[0050] In some embodiments, the first duration is determined based on the discharge duration of the large capacitor bank.

[0051] For example, the duration of the flashing stage of the gas discharge electric light source is the discharge duration of the large capacitor group. In order to reduce the impact of the charging mechanism in the undervoltage protection state on the flashing of the flashing light, the above-mentioned first duration can be determined based on the discharge duration of the large capacitor group.

[0052] In one example, the first time period is equal to the discharge time period of the large capacitor bank.

[0053] It should be noted that the first duration is not limited to being equal to the discharge duration of the large capacitor bank. The first duration can also be greater than or less than the discharge duration of the large capacitor bank. However, the difference between the first duration and the discharge duration of the large capacitor bank must be within a preset range. For example, if the first duration is too short, the flashing of the strobe light may be significantly affected; if the first duration is too long, the PFC boost circuit may not be able to enter the undervoltage protection state in a timely manner, thereby generating harmonic currents.

[0054] In some embodiments, the second duration is determined based on a charging duration of the large capacitor bank when no large capacitor bank charging control circuit is provided.

[0055] For example, considering that gas discharge electric light sources may have the need to flash multiple times in a short period of time, in order to avoid the charging time of the large capacitor group being too long, which will affect the normal execution of the gas discharge electric light source flashing multiple times in a short period of time, when increasing the charging time of the large capacitor group through the large capacitor group charging control circuit, it is necessary to avoid the charging time being too long in the undervoltage protection state.

[0056] Accordingly, the width of the pulse signal output by the MCU control circuit (ie, the second duration) may be based on the charging duration of the large capacitor group when the large capacitor group charging control circuit is not provided.

[0057] In one example, the second duration is shorter than the charging duration of the large capacitor group when the large capacitor group charging control circuit is not provided, so as to avoid the large capacitor group charging duration being too long.

[0058] See Figure 2 , is a schematic diagram of a gas discharge type electric light source provided in an embodiment of the present application, such as Figure 2 As shown, the gas discharge electric light source includes a harmonic current optimization circuit, which includes: a large capacitor bank charging control circuit, the input end of the large capacitor bank charging control circuit is connected to the MCU control circuit, and the output end is connected to the PFC control chip; wherein:

[0059] The MCU control circuit is used to output a flash trigger signal when receiving an external trigger signal, and delay the first duration to output a pulse signal with a width of the second duration.

[0060] The large capacitor bank charging control circuit is used to control the PFC control chip to enter the undervoltage protection state according to the pulse signal;

[0061] The PFC control chip is used to control the PFC boost circuit to be in the undervoltage protection state when in the undervoltage protection state;

[0062] PFC boost circuit, used to charge the large capacitor bank.

[0063] In the embodiment of the present application, it is taken into consideration that for a gas discharge type electric light source, after it completes the flash, a large capacitor group needs to be charged. Under normal circumstances, even if PFC improvement measures are deployed, when the large capacitor group is charged through the PFC boost circuit, the current will still change suddenly due to the rapid current, and further, harmonic current will be generated.

[0064] In order to reduce the harmonic current emission of gas discharge electric light sources, a large capacitor group charging control circuit can be deployed in the gas discharge electric light source. The large capacitor group charging control circuit can slow down the charging rate of the large capacitor group, increase the charging time of the large capacitor group, reduce transient power mutations, and reduce harmonic current emission.

[0065] Accordingly, in the embodiment of the present application, a harmonic current optimization circuit can be provided in the gas discharge electric light source, and the harmonic current optimization circuit can include an MCU control circuit, a large capacitor bank charging control circuit, a PFC control chip, and a PFC boost circuit.

[0066] The MCU control circuit can receive an external trigger signal, and when receiving the external trigger signal, on the one hand, it outputs a strobe trigger signal to trigger the strobe light to flash; on the other hand, it can output a pulse signal to enable the large capacitor group charging control circuit to control the PFC control chip and the PFC boost circuit to enter the undervoltage protection state. Then, in the undervoltage protection state, the PFC boost circuit slowly controls the output voltage change and slowly charges the large capacitor group.

[0067] In addition, considering that the flashing process of the flashing lamp usually lasts for a certain period of time, if the PFC boost circuit charges the large capacitor group in the undervoltage protection state during this time, it may affect the normal flashing of the flashing lamp.

[0068] Accordingly, in order to reduce the impact of the charging control of the large capacitor group on the normal flashing of the flashing light, the MCU control circuit can delay for a certain time (referred to as the first time length in this article) and output a pulse signal with a certain width of a certain time length (referred to as the second time length in this article) when receiving an external trigger signal. In this way, it can be ensured that the PFC boost circuit charges the large capacitor group in the undervoltage protection state after the MCU control circuit receives the external trigger signal for the first time length.

[0069] In some embodiments, the large capacitor bank charging control circuit may include: a transistor and an N-channel MOS (Metal-Oxide-Semiconductor Field-Effect Transistor); the base of the transistor is connected to the timing pin of the MCU control circuit, the gate of the N-channel MOS transistor is connected to the collector of the transistor, and the drain of the N-channel MOS transistor is connected to the BO pin of the PFC control chip.

[0070] For example, in order to control the PFC control chip and the PFC boost circuit to enter the undervoltage protection state, it is necessary to control the input voltage of the PFC control chip to be within a specified voltage threshold. Even if the input voltage of the PFC control chip is lower than the specified voltage threshold (which can be set according to actual scenarios), the large capacitor group charging control circuit may include a transistor and an N-channel MOS transistor.

[0071] The base of the transistor (i.e., the B pole) is connected to the timing pin of the MCU control circuit.

[0072] When the MCU control circuit receives an external trigger signal, it can delay the first duration through the timing pin to output a pulse signal with a width of the second duration.

[0073] The transistor of the large capacitor group control circuit can be turned on under the action of the pulse signal, and further, can provide a trigger signal to the N-channel MOS tube.

[0074] Exemplarily, the gate electrode (ie, the G electrode) of the N-channel MOS transistor is connected to the collector electrode (ie, the C electrode) of the transistor.

[0075] After the transistor is turned on, a trigger signal can be provided to the gate of the N-channel MOS tube through the collector.

[0076] Under the stimulation of the trigger signal, the voltage difference (V DS ) changes according to the change trajectory of cut-off region → saturation region → variable resistance region.

[0077] When VDS enters the variable resistance region, the input voltage of the BO (Brown Out) pin of the PFC control chip connected to the drain of the N-channel MOS transistor is lower than the above-mentioned specified voltage threshold, and then the PFC control chip enters the undervoltage protection state.

[0078] When the PFC control chip enters the undervoltage protection state, it can output a trigger signal to the PFC boost circuit, triggering the PFC boost circuit to also enter the undervoltage protection state, so that the PFC boost circuit can charge the large capacitor group in the undervoltage protection state.

[0079] In one example, the large capacitor bank charging control circuit may further include: an optocoupler relay; an optocoupler end of the optocoupler relay is connected to the collector of the transistor, and the other end of the optocoupler relay is connected to the gate of the N-channel MOS transistor.

[0080] For example, in order to improve circuit stability, the large capacitor group charging control circuit can also include an optocoupler relay, which can be deployed between the transistor and the N-channel MOS tube to achieve strong and weak current isolation and protect the safety of the weak current side (MCU control circuit side).

[0081] Exemplarily, the optocoupler end of the optocoupler relay may be connected to the collector of the transistor, and the other end may be connected to the gate of the N-channel MOS transistor.

[0082] When the transistor is turned on due to the pulse signal output by the MCU control circuit, the optocoupler relay will also be turned on, and then the optocoupler relay can output a trigger signal to the gate of the N-channel MOS tube.

[0083] Under the stimulation of the trigger signal, the voltage difference (V DS ) changes according to the change trajectory of cut-off region → saturation region → variable resistance region.

[0084] In V DS When entering the variable resistance region, the input voltage of the BO pin of the PFC control chip connected to the drain of the N-channel MOS transistor is lower than the above-mentioned specified voltage threshold, and then the PFC control chip enters the undervoltage protection state.

[0085] When the PFC control chip enters the undervoltage protection state, it can output a trigger signal to the PFC boost circuit, triggering the PFC boost circuit to also enter the undervoltage protection state, so that the PFC boost circuit can charge the large capacitor group in the undervoltage protection state.

[0086] In some embodiments, the first duration is determined based on the discharge duration of the large capacitor bank.

[0087] For example, the duration of the flashing stage of the gas discharge electric light source is the discharge duration of the large capacitor group. In order to reduce the impact of the charging mechanism in the undervoltage protection state on the flashing of the flashing light, the above-mentioned first duration can be determined based on the discharge duration of the large capacitor group.

[0088] In one example, the first time period is equal to the discharge time period of the large capacitor bank.

[0089] It should be noted that the first duration is not limited to being equal to the discharge duration of the large capacitor bank. The first duration can also be greater than or less than the discharge duration of the large capacitor bank. However, the difference between the first duration and the discharge duration of the large capacitor bank must be within a preset range. For example, if the first duration is too short, the flashing of the strobe light may be significantly affected; if the first duration is too long, the PFC boost circuit may not be able to enter the undervoltage protection state in a timely manner, thereby generating harmonic currents.

[0090] In some embodiments, the second duration is determined based on a charging duration of the large capacitor bank when no large capacitor bank charging control circuit is provided.

[0091] For example, considering that gas discharge electric light sources may have the need to flash multiple times in a short period of time, in order to avoid the charging time of the large capacitor group being too long, which will affect the normal execution of the gas discharge electric light source flashing multiple times in a short period of time, when increasing the charging time of the large capacitor group through the large capacitor group charging control circuit, it is necessary to avoid the charging time being too long in the undervoltage protection state.

[0092] Accordingly, the width of the pulse signal output by the MCU control circuit (ie, the second duration) may be based on the charging duration of the large capacitor group when the large capacitor group charging control circuit is not provided.

[0093] In one example, the second duration is shorter than the charging duration of the large capacitor group when the large capacitor group charging control circuit is not provided, so as to avoid the large capacitor group charging duration being too long.

[0094] In order to enable those skilled in the art to better understand the technical solutions provided by the embodiments of the present application, the technical solutions provided by the embodiments of the present application are described below with reference to specific examples.

[0095] See Figure 3A , which is a schematic diagram of a typical gas discharge type electric light source in traditional schemes.

[0096] like Figure 3A As shown, taking the traffic gas flash light as an example, the traffic gas flash light can be a gas discharge type fill light developed for speeding capture, road checkpoints and other systems. When the system's photosensitive circuit detects that the photosensitivity threshold is lower than a certain value, it automatically outputs a pulse signal (i.e. Figure 3A The external input signal is output to the MCU control circuit after passing through the optocoupler isolation circuit.

[0097] After the MCU control circuit receives the external input signal, on the one hand, it performs the flashing light flashing (large capacitor bank discharge) processing; on the other hand, it performs the large capacitor bank charging processing.

[0098] Among them, in the flashing processing flow of the flashing light, the MCU control circuit can output control signals to the full-control switch trigger circuit and the high-voltage trigger circuit respectively to control the flashing of the flashing light.

[0099] When the fully controllable switch trigger circuit receives the control signal, it controls the fully controllable switch to close, and the large capacitor group (i.e., the input capacitor in the figure) begins to discharge, powering the gas lamp;

[0100] When the high voltage trigger circuit receives the control signal, the auxiliary circuit in the control gas lamp interface is connected. At this time, the external input current (i.e. Figure 3A The AC input in the power supply (AC input) is processed by the protection filter circuit and rectification, and then the PFC boost circuit performs the boost processing (the working mechanism of the PFC boost circuit is explained in the charging process). On the one hand, it charges the large capacitor bank, and on the other hand, it powers the gas lamp.

[0101] The gas lamp flashes when powered by a large capacitor bank and external current.

[0102] When the gas lamp completes flashing, the fully controlled switch is disconnected, and the auxiliary circuit in the gas lamp interface is disconnected, and the path between the large capacitor group and the external input current and the gas lamp is disconnected.

[0103] In the large capacitor bank charging process, the MCU control circuit can output a trigger signal to the PFC control chip through the PWM voltage regulation circuit, and the PFC control chip controls the operation of the PFC boost circuit. Then, the external input current (i.e. Figure 3A The AC input in the circuit is processed by the protection filter circuit and the rectification, and then the PFC boost circuit performs the boost processing to charge the large capacitor bank. The large capacitor bank completes the energy storage and waits for the next trigger.

[0104] Please attend Figure 3B , which is a schematic diagram of a typical gas discharge type electric light source with an added harmonic current optimization circuit according to an embodiment of the present application.

[0105] like Figure 3B As shown, the harmonic current optimization circuit may include a large capacitor bank charging control circuit, the input end of the large capacitor bank charging control circuit is connected to the MCU control circuit, and the output end is connected to the PFC control chip.

[0106] exist Figure 3B In the circuit shown, after the MCU control circuit receives the external input signal, on the one hand, it performs the flashing light flashing (large capacitor bank discharge) processing; on the other hand, it performs the large capacitor bank charging processing.

[0107] Among them, in the flashing processing flow of the flashing light, the MCU control circuit can output control signals to the full-control switch trigger circuit and the high-voltage trigger circuit respectively to control the flashing of the flashing light.

[0108] When the fully controllable switch trigger circuit receives the control signal, it controls the fully controllable switch to close, and the large capacitor group (i.e., the input capacitor in the figure) begins to discharge, powering the gas lamp;

[0109] When the high voltage trigger circuit receives the control signal, the auxiliary circuit in the control gas lamp interface is connected. At this time, the external input current (i.e. Figure 3BThe AC input in the power supply (AC input) is processed by the protection filter circuit and rectification, and then the PFC boost circuit performs the boost processing (the working mechanism of the PFC boost circuit is explained in the charging process). On the one hand, it charges the large capacitor bank, and on the other hand, it powers the gas lamp.

[0110] The gas lamp flashes when powered by a large capacitor bank and external current.

[0111] When the gas lamp completes flashing, the fully controlled switch is disconnected, and the auxiliary circuit in the gas lamp interface is disconnected, and the path between the large capacitor group and the external input current and the gas lamp is disconnected.

[0112] In the large capacitor bank charging process, the MCU control circuit can, on the one hand, output a trigger signal to the PFC control chip through the PWM voltage regulation circuit, and the PFC control chip controls the operation of the PFC boost circuit, thereby controlling the external input current (i.e. Figure 3B The AC input in the circuit is boosted by the PFC boost circuit after passing through the protection filter circuit and rectification to charge the large capacitor bank. On the other hand, the MCU control circuit outputs a pulse signal to the large capacitor bank charging control circuit after a delay of T1, driving the PFC boost circuit into the undervoltage protection state, and charging the large capacitor bank in the undervoltage protection state.

[0113] It should be noted that, during the flashing process of the gas lamp, the PFC boost circuit is also needed to boost the external input current to power the gas lamp and achieve flashing. Therefore, when the MCU control circuit receives the external trigger signal, it needs to delay (such as delay T1) to control the PFC boost circuit to enter the undervoltage protection state (that is, it is necessary to first control the PFC boost circuit to work normally for a period of time (such as T1 time)) to ensure the normal realization of the gas lamp flashing.

[0114] Exemplarily, T1 may be determined based on the discharge time of the large capacitor bank.

[0115] For example, T1 can be equal to, greater than, or less than the discharge time of the large capacitor bank. However, the difference between T1 and the discharge time of the large capacitor bank must be within a preset range. For example, if T1 is too small, it may significantly affect the flashing of the flashing lamp; if T1 is too large, it may not be possible to control the PFC boost circuit to enter the undervoltage protection state in time, thereby generating harmonic currents.

[0116] and Figure 3A Compared with the circuit shown, Figure 3BIn the circuit shown, by deploying a large capacitor group charging control circuit, the MCU control circuit can delay (such as delay T1) outputting a pulse signal to the large capacitor group charging control circuit when receiving an external trigger signal, so that the large capacitor group charging control circuit drives the PFC boost circuit to enter the undervoltage protection state based on the pulse signal, and charges the large capacitor group in the undervoltage protection state to reduce harmonic current emission.

[0117] See Figure 4 , is a schematic diagram of a large capacitor bank charging control circuit provided in an embodiment of the present application, such as Figure 4 As shown, the large capacitor bank control chip may include a transistor Q1, an optocoupler relay OP1, and an N-channel MOS transistor. The base of the transistor Q1 is connected to the timing pin of the MCU control circuit, the collector of the transistor is connected to the optocoupler terminal of the optocoupler relay OP1, the other end of the optocoupler relay is connected to the gate of the N-channel MOS transistor, and the drain of the N-channel MOS transistor is connected to the BO pin of the PFC control chip.

[0118] The functions of each component are introduced below.

[0119] 1. MCU control circuit

[0120] Receive external input signals and generate strobe trigger signals. Through software programming, the delayed trigger function of the timing pin TIM_ETR can be realized, that is, the delayed output of a pulse signal with a certain width, for example, delaying the above-mentioned first duration to output a pulse signal with the above-mentioned second duration width.

[0121] 2. Transistor Q1, optocoupler relay OP1

[0122] It realizes the isolation between strong and weak electricity, receives the trigger signal of MCU (i.e. the above-mentioned pulse signal), and provides the trigger signal to the N-channel MOS tube.

[0123] 3. N-channel MOS tube:

[0124] The N-channel MOS tube is stimulated by the trigger signal output by the optocoupler relay OP1, and its opening trajectory is as follows: Figure 5 shown.

[0125] like Figure 5 As shown, A represents the cut-off region, B represents the saturation region, C / D represents the variable resistance region, and the V DS Voltage change trajectory A→B→C→D.

[0126] 4. PFC module (including PFC control chip and PFC boost circuit)

[0127] The BO pin of the PFC module is connected to the drain of the N-channel MOSFET. DSWhen entering the variable resistance area, its undervoltage protection function is triggered.

[0128] The PFC boost circuit charges the large capacitor bank in the undervoltage protection state, and the output voltage rises slowly, thereby achieving the purpose of controlling the charging time of the large capacitor bank.

[0129] In this embodiment, the flow chart of the large capacitor bank charging control can be found in Figure 6 .

[0130] like Figure 6 As shown, when the MCU control circuit receives an external trigger signal, it can generate a flash trigger signal and delay T1 (ie, the first duration) to generate a pulse signal with a width of T3 (ie, the second duration).

[0131] Based on the pulse signal output by the MCU control circuit through the timing pin, the transistor Q1 and the optocoupler relay OP1 are turned on in sequence and provide a trigger signal for the N-channel MOS tube.

[0132] The N-channel MOS tube is stimulated by the trigger signal of the optocoupler relay OP1, V DS Voltage according to Figure 5 The change trajectory shown changes.

[0133] The BO pin of the PFC control chip is at V DS When operating in the variable resistance region, the PFC boost circuit is driven into the undervoltage protection state, and the output voltage change is slowly controlled.

[0134] The PFC boost circuit slowly charges the large capacitor bank.

[0135] It should be noted that, assuming the duration of a complete strobe light flash is T0 = T1 (the flash phase, i.e., the discharge time of the large capacitor bank) + T2 (the charging time of the large capacitor bank), the MCU control circuit's timing pin, TIM_ETR, can be flexibly configured through software programming. Assuming a delay of T1, a trigger pulse with a width of T3 is output. T3 affects the turn-on time of the N-type MOSFET, ultimately determining the charging time of the large capacitor bank by the PFC boost circuit.

[0136] In actual applications, in order to reduce harmonic currents without affecting the technical specifications of the flash lamp (such as continuous flashing in a short period of time), T3 should be set to an appropriate value based on the test.

[0137] Exemplarily, T3<T2.

[0138] The effects of the technical solutions provided in the embodiments of the present application are described below in conjunction with specific applications.

[0139] Assume that the overall block diagram of a traffic gas flashing light is as follows Figure 3AAs shown, when the large capacitor bank charging control circuit is not added, the waveform measured by the oscilloscope from the AC220 port of the whole machine when the traffic flashing light is charging is as follows Figure 7A As shown, the charging time of the large capacitor bank is about 55ms.

[0140] The test results of the Harmonics tester can be Figure 7B and Figure 7C shown.

[0141] in, Figure 7B A schematic diagram of current and voltage waveforms.

[0142] Figure 7C Schematic diagram of harmonic current and Class C limit line (taking European standard as an example).

[0143] For example, the test results may be shown in Table 2:

[0144] Table 2

[0145]

[0146] The meanings of the headers in the table are as follows:

[0147] "Harm#" is the harmonic order, "Harms(avg)" is the average value of the harmonic current (test value), "100%Limit" is the limit value of the average value of the harmonic current (i.e. standard value), "%of Limit" is the ratio of the test value of the average value of the harmonic current to the standard value (percentage value), "Harms(max)" is the maximum value of the harmonic current (test value), "150%Limit" is the limit value of the maximum value of the harmonic current (i.e. standard value), "%of Limit" is the ratio of the test value of the maximum value of the harmonic current to the standard value (percentage value), "Status" is the exceedance status, "Fail" means exceedance, and "Pass" means not exceedance.

[0148] It can be seen that the harmonic current does not meet the Class C limit requirements of the standard IEC 61000-3-2:2018.

[0149] For example, after adding a large capacitor bank charging control circuit, its overall block diagram is as follows: Figure 3B As shown, the detailed parameters of the large capacitor bank charging control circuit are as follows Figure 8 shown.

[0150] For example, after adding a large capacitor bank charging control circuit, the waveform measured by the oscilloscope at the AC220 port of the whole machine can be as follows: Figure 9A As shown in Figure 1, the charging time of the large capacitor bank is 90ms, and the waveform is closer to a standard sine wave.

[0151] The test results of Harmonics tester can be Figure 9B and Figure 9C shown.

[0152] in, Figure 9B Schematic diagram of Current & voltage waveforms.

[0153] Figure 9C Schematic diagram of harmonic current and Class C standard line.

[0154] For example, the test results may be shown in Table 3:

[0155] Table 3

[0156]

[0157] It can be seen that after adding the large capacitor bank charging control circuit, the harmonic current meets the standard IEC61000-3-2:2018 Class C limit requirements.

[0158] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

[0159] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A method for controlling harmonic current emission at an AC power port, characterized in that: The method is applied to a gas discharge electric light source, wherein the gas discharge electric light source is provided with a harmonic current optimization circuit, and the harmonic current optimization circuit includes a large capacitor bank charging control circuit; the input end of the large capacitor bank charging control circuit is connected to a microcontroller unit MCU control circuit, and the output end is connected to a power factor correction PFC control chip. The method includes: The MCU control circuit receives an external trigger signal; The MCU control circuit outputs a flash trigger signal and delays the first duration to output a pulse signal with a second duration, so that the large capacitor bank charging control circuit controls the PFC control chip and the PFC boost circuit to enter an undervoltage protection state based on the pulse signal, and the PFC boost circuit charges the large capacitor bank in the undervoltage protection state; Wherein, the first duration is determined according to the discharge duration of the large capacitor bank; The second duration is determined based on a charging duration of the large capacitor group when the large capacitor group charging control circuit is not provided.

2. The method according to claim 1, characterized in that The first duration is equal to the discharge duration of the large capacitor bank; and / or, The second duration is shorter than a charging duration of the large capacitor group when the large capacitor group charging control circuit is not provided.

3. A gas discharge electric light source, characterized in that: include: A harmonic current optimization circuit, comprising a large capacitor bank charging control circuit; the input end of the large capacitor bank charging control circuit is connected to a microcontroller unit (MCU) control circuit, and the output end is connected to a power factor correction (PFC) control chip; wherein: The MCU control circuit is configured to output a strobe trigger signal when receiving an external trigger signal, and delay the first duration to output a pulse signal with a second duration; The large capacitor bank charging control circuit is used to control the PFC control chip to enter an undervoltage protection state according to the pulse signal; The PFC control chip is used to control the PFC boost circuit to be in the undervoltage protection state when in the undervoltage protection state; The PFC boost circuit is used to charge the large capacitor bank; Wherein, the first duration is determined according to the discharge duration of the large capacitor bank; The second duration is determined based on a charging duration of the large capacitor group when the large capacitor group charging control circuit is not provided.

4. The gas discharge electric light source according to claim 3, characterized in that: The large capacitor group charging control circuit includes: a transistor and an N-channel MOS transistor; the base of the transistor is connected to the timing pin of the MCU control circuit, the gate of the N-channel MOS transistor is connected to the collector of the transistor, and the drain of the N-channel MOS transistor is connected to the undervoltage protection BO pin of the PFC control chip.

5. The gas discharge electric light source according to claim 4, characterized in that: The large capacitor group charging control circuit also includes: an optocoupler relay; the optocoupler end of the optocoupler relay is connected to the collector of the transistor, and the other end of the optocoupler relay is connected to the gate of the N-channel MOS transistor.

6. The gas discharge electric light source according to claim 3, characterized in that: The first duration is equal to the discharge duration of the large capacitor bank; and / or, The second duration is shorter than a charging duration of the large capacitor group when the large capacitor group charging control circuit is not provided.

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