An alternating current circuit series capacitance value detection circuit

Abstract

The utility model relates to the technical field of household appliances, concretely say is the detection circuit of series capacitor value in alternating current circuit. Its characteristics include that the voltage sampling circuit and the controller of DC brushless motor are connected with the output end a of speed regulator through the controller, the upper end of the voltage dividing resistor is used to be connected with the output end a of speed regulator, and the lower end of the voltage dividing resistor is connected with the zero line N of alternating current, the voltage sampling circuit is connected with the voltage dividing resistor adaptation, is used for collecting the voltage of both ends of voltage dividing resistor, and the voltage of both ends of voltage dividing resistor is delivered to the controller. The convenience of adopting the circuit is good.

Description

Technical Field

[0001] This utility model relates to the field of household appliance technology, specifically to a circuit for detecting the capacitance value of a series capacitor in an AC circuit. Background Technology

[0002] Many AC motors used both domestically and internationally still regulate speed by adjusting the capacitance of the capacitor connected in series on the grid side, such as household ceiling fans. The circuit structure is as follows: Figure 1 As shown. With the development of brushless DC motors and the advancement of control technology, using brushless DC motors and controllers to replace AC motors is becoming increasingly economical. There is a large stock of such products; therefore, the current technical approach is to directly replace AC motors with brushless motors and controllers in existing products, with the circuit structure as shown. Figure 2 As shown. However, the capacitor connected in series on the grid side is usually together with the speed control switch. After replacement, it is necessary to redetermine the new speed controller gear based on the grid side capacitor. This requires a professional to obtain the capacitance value of each speed controller gear using specialized equipment and then set it separately, which is not very convenient. Utility Model Content

[0003] The technical problem to be solved by this utility model is to provide a detection circuit for the capacitance value of a series capacitor in an AC circuit, which is convenient to use.

[0004] To solve the above problems, the following technical solution is adopted: The detection circuit for the series capacitor value in the AC circuit of this utility model is characterized by including a voltage divider resistor, a voltage sampling circuit, and a controller for a brushless DC motor. The output terminal a of the speed controller is connected to the brushless DC motor through the controller. The upper end of the voltage divider resistor is connected to the output terminal a of the speed controller, and the lower end of the voltage divider resistor is connected to the neutral line N of the AC power supply. The voltage sampling circuit is adapted to the voltage divider resistor and is used to collect the voltage across the voltage divider resistor and transmit the voltage across the voltage divider resistor to the controller.

[0005] The speed controller includes a speed control switch and at least two speed control positions. The resistance of each speed control position is different. The first end of each speed control position is connected to the output terminal a of the speed controller. One end of the speed control switch is connected to the live wire L of the AC power supply. The other end of the speed control switch is used to switch between the second ends of different speed control positions to achieve speed regulation.

[0006] There are 5 speed settings: slow, second slow, medium, second fast, and fast. Each of the slow, second slow, medium, and second fast settings has a capacitor connected in series, and the capacitance value of the capacitor increases from slow to second slow, medium to second fast.

[0007] There is no series capacitor on the fast mode.

[0008] The voltage divider resistors include voltage divider resistor 1, voltage divider resistor 2, and voltage divider resistor 3, which are connected in series between the output terminal a of the speed controller and the neutral line N of the AC power supply. The voltage sampling circuit includes an operational amplifier U1. The non-inverting input terminal of the operational amplifier U1 is connected to one end of resistor R1 and resistor R4, respectively. The other end of resistor R1 is connected to the pull-up power supply and the upper end of voltage divider resistor 2, respectively. The other end of resistor R4 is grounded. The inverting input terminal of the operational amplifier U1 is connected to one end of resistor R2 and resistor R3, respectively. The other end of resistor R2 is connected to the lower end of voltage divider resistor 2, and the other end of resistor R3 is connected to the output terminal of the operational amplifier U1. The output terminal of the operational amplifier U1 outputs a VOUT signal to the controller.

[0009] The above approach has the following advantages: In this invention, the output terminal a of the speed controller in the AC circuit series capacitor value detection circuit is connected to the DC brushless motor via the controller. The upper end of the voltage divider resistor is connected to the output terminal a of the speed controller, and the lower end of the voltage divider resistor is connected to the neutral line N of the AC power supply. The voltage sampling circuit is adapted to the voltage divider resistor to collect the voltage across the voltage divider resistor and transmit the voltage across the voltage divider resistor to the controller. This circuit is integrated into the controller circuit of the brushless motor. After replacing the AC motor with the brushless motor and controller, the operator sequentially turns on the speed controller gears. The voltage values ​​obtained by connecting the resistor in series with different capacitor values ​​are different. Through the voltage sampling circuit, this signal is input to the DC brushless motor controller chip for detection, thus determining the current capacitor value. The controller can then set the gear according to the current capacitor value, thereby eliminating the need for professional operation and greatly improving the convenience of replacement. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of a speed control circuit for an existing AC motor in the background art; Figure 2 This is a schematic diagram of a speed control circuit in the background technology that uses a brushless motor and controller to replace an AC motor; Figure 3 This is a schematic diagram of the structure of the detection circuit for the capacitance value of the series capacitor in the AC circuit of this utility model; Figure 4 This is a schematic diagram of the voltage sampling circuit in the AC circuit of this utility model, which is used to detect the capacitance value of the series capacitor. Detailed Implementation

[0011] The present invention will be further described in detail below with reference to the accompanying drawings.

[0012] like Figure 3As shown, the detection circuit for the series capacitor value in the AC circuit of this utility model includes a voltage divider resistor, a voltage sampling circuit, and a controller for a brushless DC motor. The output terminal a of the speed controller is connected to the brushless DC motor through the controller. The upper end of the voltage divider resistor is connected to the output terminal a of the speed controller, and the lower end of the voltage divider resistor is connected to the neutral line N of the AC power supply. The voltage sampling circuit is adapted to the voltage divider resistor to collect the voltage across the voltage divider resistor and transmit the voltage across the voltage divider resistor to the controller.

[0013] In this embodiment, the specific model and circuit structure of the controller can be selected by those skilled in the art as needed, and are considered existing technology, so they will not be described in detail here. The AC power is 220V AC.

[0014] In this embodiment, as Figure 3 As shown, the speed controller includes a speed control switch and at least two speed settings. The resistance of each speed setting is different. The first terminal of each speed setting is connected to the output terminal a of the speed controller. One end of the speed control switch is connected to the live wire L of the AC power supply. The other end of the speed control switch is used to switch between the second terminals of different speed settings to achieve speed regulation. There are five speed settings: slow, medium, medium, medium-fast, and fast. Each of the slow, medium, and fast speed settings has a capacitor connected in series. From slow to medium to fast, the larger the capacitance of the capacitor, the smaller its internal resistance. The fast speed setting has no capacitor connected in series, therefore its resistance is the smallest, thus achieving speed regulation from slow to fast. The specific structure of the speed control switch in this embodiment is prior art and will not be described further here.

[0015] In this embodiment, as Figure 3 As shown, add appropriate voltage divider resistors (resistance values ​​can be selected between 100 and 100kΩ) across node ab. Since the voltage values ​​obtained by connecting the resistors in series with different capacitance values ​​are different, this signal is input to the DC brushless motor controller chip for detection through the voltage sampling circuit, so that the current capacitance value can be determined. The controller can then sample based on the current capacitance value.

[0016] like Figure 4As shown, the voltage divider resistors include voltage divider 1, voltage divider 2, and voltage divider 3, which are connected in series between the output terminal a of the speed controller and the neutral line N of the AC power supply. The voltage sampling circuit includes an operational amplifier U1. The non-inverting input terminal of operational amplifier U1 is connected to one end of resistor R1 and resistor R4, respectively. The other end of resistor R1 is connected to the pull-up power supply and the upper end of voltage divider 2, respectively. The other end of resistor R4 is grounded. The inverting input terminal of operational amplifier U1 is connected to one end of resistor R2 and resistor R3, respectively. The other end of resistor R2 is connected to the lower end of voltage divider 2, and the other end of resistor R3 is connected to the output terminal of operational amplifier U1. The output terminal of operational amplifier U1 outputs a VOUT signal to the controller. In this embodiment, the pull-up power supply is VCC / 2. The formation of VCC is prior art and will not be described in detail here.

[0017] The circuitry of this solution is integrated into the controller circuit of the brushless motor. After replacing the AC motor with the brushless motor and controller, the operator sequentially switches the speed controller to different speed settings. The voltage values ​​obtained by connecting the resistor and the capacitor in series are different. This signal is input to the DC brushless motor controller chip for detection through a voltage sampling circuit, which determines the current capacitance value. The controller can then set the speed setting based on the current capacitance value, thus eliminating the need for professional operation and greatly improving the convenience of replacement.

Claims

1. A circuit for detecting the capacitance value of a series capacitor in an AC circuit, characterized in that, The system includes a voltage divider resistor, a voltage sampling circuit, and a controller for a brushless DC motor. The output terminal a of the speed controller is connected to the brushless DC motor through the controller. The upper end of the voltage divider resistor is connected to the output terminal a of the speed controller, and the lower end of the voltage divider resistor is connected to the neutral line N of the AC power supply. The voltage sampling circuit is adapted to the voltage divider resistor and is used to collect the voltage across the voltage divider resistor and transmit the voltage across the voltage divider resistor to the controller.

2. The series capacitor value detection circuit in an AC circuit as described in claim 1, characterized in that, The speed controller includes a speed control switch and at least two speed control positions. The resistance of each speed control position is different. The first terminal of each speed control position is connected to the output terminal a of the speed controller. One end of the speed control switch is connected to the live wire L of the AC power supply. The other end of the speed control switch is used to switch between the second terminals of different speed control positions to achieve speed regulation.

3. The series capacitor value detection circuit in an AC circuit as described in claim 2, characterized in that, There are 5 speed settings: slow, second slow, medium, second fast, and fast. Each of the slow, second slow, medium, and second fast settings has a capacitor connected in series, and the capacitance value of the capacitor increases from slow to second slow, medium to second fast.

4. The series capacitor value detection circuit in an AC circuit as described in claim 3, characterized in that, There is no series capacitor on the fast mode.

5. The series capacitor value detection circuit in an AC circuit as described in claim 1, characterized in that, The voltage divider resistors include voltage divider resistor (1), voltage divider resistor (2), and voltage divider resistor (3), which are connected in series between the output terminal a of the speed controller and the neutral line N of the AC power supply; the voltage sampling circuit includes an operational amplifier U1, the non-inverting input terminal of the operational amplifier U1 is connected to one end of resistor R1 and resistor R4 respectively, the other end of resistor R1 is connected to the pull-up power supply and the upper end of the voltage divider resistor (2) respectively, and the other end of resistor R4 is grounded; the inverting input terminal of the operational amplifier U1 is connected to one end of resistor R2 and resistor R3 respectively, the other end of resistor R2 is connected to the lower end of the voltage divider resistor (2), and the other end of resistor R3 is connected to the output terminal of the operational amplifier U1; the output terminal of the operational amplifier U1 outputs a VOUT signal to the controller.

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