For single live wire switch dummy load circuit and electrical load

Abstract

The present invention relates to a dummy load circuit for a single live wire switch. The dummy load circuit comprises: a switch circuit, in which at least a first resistor and a switch are connected, wherein the first resistor is connected to the switch, so that the first resistor is connected to the dummy load circuit through the switch; and a switch control circuit, wherein the switch control circuit comprises at least a switch control device, and the switch control device is connected to the switch so as to control the switch. The present invention also relates to an electrical load having a dummy load circuit.

Description

Technical Field

[0001] The invention relates to a dummy load circuit for a single live wire switch and an electrical appliance load. Background Art

[0002] At present, two-wire smart switches (dimmers) with single wireless modes (Zigbee, BT, etc.) are commonly seen in the market. Such two-wire smart switches are called single-live-wire smart switches. They can be used to be compatible with a variety of electrical load types, such as LED lights, fans, traditional tungsten filament lamps, etc.

[0003] It is now also expected that a dual-wire smart switch with dual wireless mode (e.g., BLE+WiFi) can be designed. However, this faces great challenges in terms of load power supply, because in dual wireless mode (e.g., BLE+WiFi), the energy consumption of the smart switch is about 4-5 times that of the single wireless mode.

[0004] In single wireless mode, single live wire smart switches already have ghost fire and flickering problems. Because single live wire smart switches do not have a neutral wire, but are only connected to the live wire, the switch draws power through the load current. That is to say, even if the load is turned off normally, a certain current will flow through the load to maintain the operation of the switch.

[0005] In dual wireless mode, combined with the more significant energy consumption of the single-live smart switch, the ghost fire and flickering problem of the switch is more difficult to overcome, and it is also difficult to ensure the normal energy consumption of the single-live smart switch when some electrical loads are turned on normally. On the one hand, in this application scenario, the different load types that need to be compatible are more complex, which also makes the compatibility worse. For example, smart LED lights and non-dimming LED lights are difficult to be compatible, so they will flicker when turned on and have ghost fire when turned off. In addition, in dual wireless mode, the zero-crossing detection of the single-live smart switch is also a big problem.

[0006] In order to solve the flicker and ghost fire problems, in the single wireless mode, X2 capacitors have been used as dummy loads to solve compatibility issues. The dummy load is connected in parallel with the electrical load. However, X2 capacitors are not suitable for dual wireless mode. This is because, due to the limited capacitance capacity, X2 capacitors cannot provide enough current for the dual wireless mode single live wire smart switch to draw power. If X2 capacitors are used as dummy loads, very obvious ghost fire phenomena may be observed. In addition, X2 capacitors cannot provide very accurate zero-crossing detection functions for all electrical loads.

[0007] If a pure resistor is used as the load, although most of the above requirements can be met, it will also cause a power consumption of more than 8W in the turned-on state, which is basically unacceptable in the application. Summary of the invention

[0008] In order to overcome the above problems, the present invention proposes a dummy load circuit for a single live wire switch and an electrical load having the dummy load circuit, which reduces power consumption when turned on and does not produce ghost fires when turned off, while also providing accurate zero-crossing detection.

[0009] In this application, the term "single live wire switch" has the same meaning as the term "single live wire intelligent switch".

[0010] According to the present invention, a dummy load circuit for a single live wire switch comprises:

[0011] a switch circuit, in which at least a first resistor and a switch are connected, wherein the first resistor is connected to the switch, so that the first resistor is connected to the dummy load circuit through the switch; and

[0012] The switch control circuit at least includes a switch control device, and the switch control device is connected to the switch so as to control the switch.

[0013] In the dummy load circuit of the present invention, the switch is controlled by means of a switch control device, and the first resistor in the dummy load circuit is connected to the circuit of the system within the lower voltage range of each cycle of the mains power, and the first resistor in the dummy load circuit is disconnected within the higher voltage range of each cycle of the mains power. When the system is turned off, the first resistor of the dummy load circuit provides most of the system's power, thereby also avoiding ghost lights of the lamp load. By connecting the first resistor when needed, when using the dummy load circuit according to the present invention, the power consumption of the single live wire switch is significantly reduced and has particularly good thermal performance.

[0014] In one embodiment of the present invention, when the voltage on the dummy load circuit rises from zero to a first threshold value, the switch is turned on, and when the voltage continues to rise to a second threshold value, the switch control device turns the switch off. When the voltage on the dummy load circuit drops from a high voltage to a third threshold value, the switch control device turns the switch on, and when the voltage continues to drop to a fourth threshold value of the switch, the switch turns off autonomously. Thus, a threshold interval for the switch is formed. The upper limit value of the threshold interval is, for example, a voltage value at which the lamp load will not work. Therefore, the upper limit value of the threshold interval can be preset and can be set according to the electrical parameters of the electrical load. According to the preset upper limit value of the threshold interval, for example, it can be ensured that the electrical load stably draws power in the turned-on state or will not be affected by ghost lights caused by the current drawn by the single-live-wire switch in the turned-off state. Thus, the compatibility of the single-live-wire switch with different types of electrical loads is improved by means of the dummy load circuit.

[0015] In one embodiment of the present invention, the switch control circuit further includes a pure resistance circuit, which is used to provide a pure resistance path for the single live wire switch to help achieve accurate zero-crossing point detection, and the pure resistance circuit includes at least one other resistor, the voltage on the other resistor is proportional to the threshold of the switch, and the pure resistance circuit is connected to the switch control device, so that the switch control device operates according to the voltage on the other resistor. The pure resistance circuit can be composed of multiple other resistors, or it has only one other resistor.

[0016] On the one hand, by adjusting the resistance of the pure resistance circuit, the upper limit of the threshold interval matching different types of electrical loads can be achieved. On the other hand, the pure resistance circuit is connected between the input and output ends of the dummy load circuit, so that the pure resistance circuit is connected in parallel with the electrical load. In this way, during zero-crossing detection, the resistance of the pure resistance circuit can help the single live wire switch accurately detect the zero-crossing point of the mains voltage.

[0017] In the case of conventional electrical loads, such as lamp loads, although zero-crossing detection is also performed, the zero-crossing detection is generally performed on the mains. The inventors have noticed that this conventional zero-crossing detection is not applicable to the case where the electrical loads are connected in series. In the series circuit of the electrical loads, what is detected by the single live wire switch is not the conventional mains voltage, but the voltage between the load and the live wire of the power grid. If the series electrical loads do not provide a purely resistive path to the mains, zero-point detection distortion will result. In the present invention, the zero-point detection offset caused by certain electrical loads can be compensated by a pure resistance circuit. Therefore, by setting up a pure resistance circuit, the single live wire switch can achieve more accurate zero-crossing detection.

[0018] In one embodiment of the present invention, a rectifier circuit is also connected between the input end of the dummy load circuit and the switch circuit and the switch control circuit. The rectifier circuit rectifies the alternating current into direct current. In addition, different rectifier circuits can be designed according to the type of electrical load. For example, the rectifier circuit can be implemented in the form of a rectifier bridge. When the switch is a MOS tube, the bidirectional conduction of the switch can be achieved through the rectifier bridge, so that the first resistor of the dummy load circuit can be connected in both half-wave cycles of the sinusoidal voltage signal of the alternating current. The rectifier circuit can also be implemented in the form of a diode. In the case of a diode, the first resistor of the dummy load circuit is only connected in one half-wave cycle of the sinusoidal voltage signal. In the present invention, the design of the rectifier circuit matches the type of electrical load. Those skilled in the art can design a variety of rectifier circuits as needed, such as a full bridge, a half bridge, a direct-pull circuit, etc.

[0019] In another embodiment of the present invention, a voltage limiting clamp circuit is connected between the input end of the dummy load circuit and the switch circuit and the switch control circuit. The voltage limiting clamp circuit can be formed by a voltage limiting clamp such as a clamp diode, a thermistor, a varistor, etc. in a conventional manner.

[0020] Furthermore, the present invention also relates to an electrical load having the dummy load circuit according to the present invention, in particular, an LED lamp, a fan, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings constitute a part of this specification and are used to help further understand the present invention. These drawings illustrate embodiments of the present invention and are used together with the specification to explain the principles of the present invention. In the accompanying drawings, the same components are represented by the same reference numerals. The drawings show:

[0022] Figure 1 Showing the principle diagram of the present invention;

[0023] Figure 2 A schematic circuit diagram showing an embodiment of a dummy load circuit according to the present invention;

[0024] Figure 3 A voltage-current waveform diagram of a single live wire switch according to an embodiment of the present invention is shown;

[0025] Figure 4 A voltage waveform diagram showing a single live wire switch in a closed state according to an embodiment of the present invention;

[0026] Figure 5 A voltage-current waveform diagram is shown when a single live wire switch according to an embodiment of the present invention is in an open state.

[0027] Reference numerals:

[0028] V(mains): input grid voltage;

[0029] V(l_Load): voltage of electrical load and dummy load circuit;

[0030] V(mains,L_load): voltage of single live wire switch;

[0031] I(Fuse): Input current of the dummy load circuit

[0032] I(R1): Current on the first resistor

[0033] V(l_Load)*I(Fuse): Energy consumption of dummy load circuit DETAILED DESCRIPTION

[0034] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only embodiments of a part of the present invention, not all embodiments. Based on the embodiments of the present invention, all other solutions obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0035] Figure 1 The principle diagram of the present invention is shown. Figure 1 As shown, the single live wire switch and the electrical load are connected to the live wire, and the electrical load and the dummy load circuit according to the present invention are connected in parallel between the live wire and the neutral wire. Figure 1 In the embodiment, the dummy load circuit according to the present invention comprises: a fuse; a rectifier circuit; a switch control circuit; and a switch circuit. Here, the switch control circuit comprises a pure resistance circuit and a switch control device. The switch circuit comprises a first resistor and a switch.

[0036] Figure 2 A schematic circuit diagram of an embodiment of a dummy load circuit according to the present invention is shown. In a system circuit consisting of a single live wire switch and an electrical load AL, the dummy load circuit according to the present invention is shown in a dotted box. It includes: a fuse F; a rectifier bridge BD1; a switch circuit consisting of a first resistor R1 and a first switch Q1; a switch control circuit consisting of a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5 and a switch control device Q2; and a sixth resistor R6 between the fuse F and the rectifier bridge and connected in parallel with the electrical load.

[0037] Here, the first switch Q1 is a MOS transistor, and the switch control device Q2 is a BJT transistor. The drain of the MOS transistor Q1 is connected to one end of the first resistor R1, and its source is grounded. The gate of the MOS transistor Q1 is connected to the collector of the transistor Q2, and a fourth resistor R4 is also connected upstream of the gate and the collector.

[0038] The emitter of transistor Q2 is grounded and the base is connected to one end of a fifth resistor. The fifth resistor is connected to a pure resistance circuit formed by the second resistor R2 and the third resistor R3, specifically, it is connected between the second resistor R2 and the third resistor R3.

[0039] like Figure 2 As shown, the dummy load circuit is connected in parallel with the electrical load AL as a whole. Here, the electrical load AL is, for example, an LED lamp. The single-live switch, i.e., the power supply and control module, is connected in series upstream of the electrical load on the live wire, and the switch and power supply functions of the single-live switch, i.e., the function of turning on and off the electrical load, are realized by switches S1 and S2.

[0040] exist Figure 2 In the illustrated embodiment, the respective thresholds for the switches are set by adjusting the values ​​of the second resistor, the third resistor, and the fifth resistor.

[0041] When the voltage Vd on the dummy load circuit starts to rise from zero and reaches the first threshold, the MOS tube is turned on and the first resistor R1 is connected, so that the current flows through the rectifier bridge BD1, the first resistor R1, and the MOS tube Q1 to form a loop.

[0042] When the voltage Vd rises from zero to the second threshold value Vdt, the transistor Q2 is in a saturated state and is turned on, so that the current flows from the collector of the transistor Q2 to the emitter. Since the collector of the transistor Q2 is connected to the gate of the MOS tube, the MOS tube is disconnected at this time, so that the first resistor R1 is also disconnected. Therefore, the current flows through the rectifier bridge BD1, the fourth resistor and the transistor Q2 to form a loop.

[0043] In the case where the voltage Vd on the dummy load circuit drops from a high voltage level, when the voltage Vd drops to the third threshold, the transistor Q2 is in a cut-off state, so that no current flows between the collector and the emitter of the transistor Q2. Here, the third threshold can be equal to the second threshold Vdt, but obviously, the two can also be different according to the needs. Therefore, the MOS tube is turned on again, and the first resistor R1 is connected. When the voltage Vd drops to the fourth threshold (zero value), the MOS tube is turned off and the first resistor R1 is also disconnected from the dummy load circuit. Here, the fourth threshold can be equal to the first threshold, but obviously, the two can also be different according to the needs.

[0044] Figures 3 to 5 The voltage-current waveform of the single live wire switch is shown when the system is in the on and off states.

[0045] Figure 3 The input grid voltage V(mains), the voltage V(l_Load) of the electrical load and the dummy load circuit, the voltage V(mains,L_load) of the single live wire switch, the input current I(Fuse) of the dummy load circuit, and the current I(R1) on the first resistor are shown. Among them, the input grid voltage V(mains) is in the form of a symmetrical sine wave. The voltage V(l_Load) of the electrical load and the dummy load circuit in a semi-elliptical shape is also shown. At both ends of the voltage V(l_Load), the current I(R1) on the first resistor with sharp protrusions can be clearly seen. This shows that the first resistor is connected at this time. After the first resistor is connected, the current flows through the power input stage capacitor of the single live wire switch and charges it.

[0046] Figure 4The voltage V(l_Load) of the electrical load and dummy load circuit and the voltage V(mains,L_load) of the single live wire switch in the off state are shown. The voltage V(l_Load) of the electrical load and dummy load circuit decreases gradually from left to right. The voltage V(mains,L_load) of the single live wire switch increases gradually from left to right. It can be seen that when the electrical load is turned off, the single live wire switch can also draw power stably and the voltage fluctuates regularly.

[0047] Figure 5 The energy consumption V(l_Load)*I(Fuse) of the dummy load circuit in the on state, the voltage V(l_Load) of the electrical load and the dummy load circuit, the input current I(Fuse) of the dummy load circuit, and the current I(R1) on the first resistor are shown. It can be seen that when the single-live switch is fully turned on, the highest energy consumption does not exceed 1.6W. On average, its energy consumption is less than 0.3W. After testing, within the 40ms interval, the average energy consumption is 215.73mW and the total energy is 8.6294mJ. A conventional dummy load with the same performance (such as a pure resistor) consumes about 8W of energy and faces extremely serious thermal overload and energy loss problems.

[0048] Therefore, compared with the pure resistor conventionally used in the prior art, the dummy load circuit of the present invention greatly reduces the power consumption of the single live wire switch. Therefore, even in the high-energy-consuming dual wireless mode, the single live wire switch can be compatible with different types of electrical loads without causing problems such as flickering, ghost fire or even short circuit.

[0049] In addition, in the present invention, by using the pure resistance circuit composed of the second resistor R2 and the third resistor R3, compensation for the electrical load AL is also achieved in the zero-crossing detection. During the zero-crossing detection, since the single live wire switch is only connected to the live wire, and it may be in a series circuit composed of multiple electrical loads, the voltage zero-crossing point detected by the single live wire switch will be affected by some electrical loads without a pure resistive path and distorted. With the help of the pure resistance circuit, the distortion of this voltage zero-crossing detection can be compensated. Therefore, the dummy load circuit according to the present invention also provides the possibility of performing accurate zero-crossing detection in the single live wire switch.

[0050] Although in Figure 2 In the circuit shown, the pure resistance circuit and the sixth resistor exist at the same time, but in one embodiment of the present invention, only the sixth resistor connected behind the fuse F can be used. This can also achieve compensation for the load resistance of the electrical appliance. Of course, the number of resistors included in the pure resistance circuit can also be set according to actual needs, as long as its function of compensating for the load resistance of the electrical appliance is maintained.

[0051] In an alternative embodiment of the present invention, a rectifier bridge is not used for rectification, but a diode is used. In the case of using a diode, the first resistor R1 of the dummy load circuit can only be connected in one half-wave. This can be achieved according to the type of electrical load.

[0052] Despite Figure 1 and Figure 2 In the figure, the single live wire switch and the dummy load circuit are shown as two separate parts, but it is also conceivable to integrate the single live wire switch with the electrical load, which also achieves higher user-friendliness.

[0053] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A dummy load circuit for a single live wire switch, characterized in that: The dummy load circuit comprises: a switch circuit, in which at least a first resistor and a switch are connected, wherein the first resistor is connected to the switch, so that the first resistor is connected to the dummy load circuit through the switch; and A switch control circuit, the switch control circuit at least comprising a switch control device, the switch control device is connected to the switch so as to control the switch, When the voltage on the dummy load circuit rises from zero to a first threshold, the switch is turned on; when the voltage continues to rise to a second threshold, the switch control device turns off the switch; when the voltage on the dummy load circuit drops from a high voltage to a third threshold, the switch control device turns on the switch; when the voltage continues to drop to a fourth threshold, the switch is autonomously turned off.

2. The dummy load circuit according to claim 1, characterized in that: The switch control circuit also includes a pure resistance circuit, which is used to provide a pure resistance path for the single-live wire switch to assist in zero-crossing detection. The pure resistance circuit includes at least one other resistor, the voltage across the other resistor is proportional to the threshold of the switch, and the pure resistance circuit is connected to the switch control device, so that the switch control device operates according to the voltage across the other resistor.

3. The dummy load circuit according to claim 1 or 2, characterized in that: A rectifier circuit is also connected between the input end of the dummy load circuit and the switch circuit and the switch control circuit.

4. The dummy load circuit according to claim 3, characterized in that: The rectifier circuit includes a rectifier bridge.

5. The dummy load circuit according to claim 3, characterized in that: The rectifying circuit includes a diode.

6. The dummy load circuit according to claim 1 or 2, characterized in that: A voltage limiting clamping circuit is also connected between the input end of the dummy load circuit and the switch circuit and the switch control circuit.

7. The dummy load circuit according to claim 1 or 2, characterized in that: The dummy load circuit is connected in parallel with the electrical load of the single live wire switch.

8. An electrical load, characterized in that: A dummy load circuit according to any one of claims 1 to 7 is provided.

9. The electrical load according to claim 8, characterized in that: The electrical load is an LED lamp.

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