Zero cross detection circuit of alternating current PTC heater

Abstract

The utility model provides a zero cross detection circuit of an AC PTC heater, the detection circuit comprises a photoelectric coupler module and a rectifier module, the rectifier module comprises a plurality of rectifier diodes, the photoelectric coupler module comprises a photoelectric coupler and a pull-up voltage source, one side of the rectifier module is also connected with an AC power supply, and the other side of the rectifier module is connected with a power supply. And one side of the photoelectric coupler module is also connected with the MCU. The rectification module converts input alternating current into one-way pulsating direct current and transmits the one-way pulsating direct current to the photoelectric coupler module, a photoelectric coupler detects rectified voltage, if the amplitude of the rectified voltage is larger than 0, the photoelectric coupler is kept in a conducting state, and the MCU detects that the input is low level; and if the voltage amplitude after rectification is 0, namely the alternating current input amplitude is 0, namely the alternating current is reversed, the photoelectric coupler is cut off, and the MCU detects that the voltage input is a high level. The zero-crossing detection circuit can quickly judge the zero-crossing moment of the alternating-current input voltage of the alternating-current PTC heater and feed back information to the MCU so as to realize accurate control of the alternating-current PTC heater.

Description

Technical Field

[0001] The utility model relates to the technical field of zero-crossing detection circuits, in particular to a zero-crossing detection circuit for an AC PTC heater. Background Art

[0002] New energy vehicles have developed rapidly in recent years. As one of the core components, the performance of the electric drive system directly affects the power output and energy efficiency of the vehicle. In the electric drive system, PTC heaters, as a highly efficient heating device, are widely used in heating battery packs and heating the air conditioning system in the car. The working principle of PTC heaters is to use the property of positive temperature coefficient materials that generate heat when current passes through them, and adjust the heating power by controlling the current size, thereby achieving precise temperature control.

[0003] However, in order to ensure the efficient and safe operation of the AC PTC heater, its working state must be precisely controlled. As a key part of the control circuit, the zero-crossing detection circuit is used to feed back the zero point of the AC power to the MCU to achieve precise control of the AC PTC heater.

[0004] In the electric drive system of new energy vehicles, the design and implementation of zero-crossing detection circuits are of great significance for improving the energy efficiency of the vehicle, ensuring the comfort of passengers, and extending the service life of the battery. With the continuous advancement of new energy vehicle technology, the performance requirements for zero-crossing detection circuits are becoming higher and higher, which requires continuous exploration and innovation to meet the needs of the market and users. Utility Model Content

[0005] The purpose of the utility model is to provide a zero-crossing detection circuit for an AC PTC heater, and to provide an AC input detection solution for the AC PTC heater. The specific technical solution is as follows:

[0006] A zero-crossing detection circuit for an AC PTC heater comprises a photoelectric coupler module and a rectifier module, wherein the rectifier module comprises a plurality of rectifier diodes, and the photoelectric coupler module comprises a photoelectric coupler and a pull-up voltage source;

[0007] The first rectifier diode and the second rectifier diode are connected in series to form a first branch, the third rectifier diode and the fourth rectifier diode are connected in series to form a second branch, the first branch and the second branch are connected in parallel to form the rectifier module, the negative terminal of the rectifier module is connected to the LED anode pin of the photoelectric coupler, and the positive terminal of the rectifier module is connected to the LED cathode pin of the photoelectric coupler;

[0008] The midpoint of the first branch is connected to the L end of the alternating current, and the midpoint of the second branch is connected to the N end of the alternating current.

[0009] Furthermore, it also includes a first resistor between the midpoint of the first branch and the AC port, and a second resistor between the midpoint of the second branch and the AC port, and the resistance values ​​of the first resistor and the second resistor are equal.

[0010] Furthermore, it also includes a third resistor between the negative terminal of the rectifier module and the LED anode pin of the photoelectric coupler.

[0011] Furthermore, the photocoupler also has a photodetector emitter pin and a photodetector collector pin, the photodetector emitter pin is grounded, and the photodetector collector pin is connected to a pull-up voltage source and a detect terminal.

[0012] Furthermore, the pull-up voltage source includes a pull-up resistor, a filter capacitor, and a 5V power supply connected to the other end of the pull-up resistor.

[0013] Furthermore, the detect terminal is connected to the MCU.

[0014] The utility model provides a zero-crossing detection circuit for an AC PTC heater, which has the following beneficial effects:

[0015] The utility model provides an AC PTC heater zero-crossing detection circuit, which can quickly determine the zero-crossing moment of the AC input voltage of the AC PTC heater and feed back the information to the MCU to achieve accurate control of the AC PTC heater. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The utility model provides a connection diagram of a zero-crossing detection circuit of an AC PTC heater. DETAILED DESCRIPTION

[0017] The following will be combined with the accompanying drawings provided by the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. According to the following description, the advantages and features of the utility model will be clearer. It should be noted that the drawings are all in a very simplified form and are not in precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the utility model.

[0018] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connection" and "connected" should be interpreted in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0019] In the description of the present invention, terms such as "upper", "lower", "left", "right", "front", "back", "center", "horizontal", "vertical", "top", "bottom", "inside" and "outside" and other orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of description and simplification of operation, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0020] Embodiment: This embodiment provides a zero-crossing detection circuit for an AC PTC heater, which includes a photocoupler module and a rectifier module, wherein the rectifier module includes multiple rectifier diodes, the photocoupler module includes a photocoupler and a pull-up voltage source, one side of the rectifier module is connected to an AC power supply, and one side of the photocoupler module is connected to an MCU.

[0021] The above zero-crossing detection circuit provided by the utility model, the rectifier module converts the input AC power into unidirectional pulsating DC power and transmits it to the photoelectric coupler module, the photoelectric coupler detects the voltage after rectification, if the voltage amplitude after rectification is greater than 0, the photoelectric coupler remains on, and the MCU detects the input as a low level; if the voltage amplitude after rectification is 0, that is, the AC input amplitude is 0, that is, when the AC is commutated, the photoelectric coupler will be cut off, and the MCU detects the voltage input as a high level. The zero-crossing detection circuit can quickly determine the zero-crossing moment of the AC input voltage of the AC PTC heater, and feed back the information to the MCU to achieve precise control of the AC PTC heater.

[0022] The overcurrent detection circuit is described in detail below.

[0023] See also Figure 1 As shown, the rectifier module of the detection circuit includes a first rectifier diode D1, a second rectifier diode D2, a third rectifier diode D3, and a fourth rectifier diode D4. The first rectifier diode D1 and the second rectifier diode D2 are connected in series to form a first branch, the third rectifier diode D3 and the fourth rectifier diode D4 are connected in series to form a second branch, and the first branch and the second branch are connected in parallel to form a rectifier module. The midpoints of the two branches of the rectifier module are respectively connected to the L end and the N end of the alternating current, that is, the L end of the alternating current is connected between the first rectifier diode D1 and the second rectifier diode D2, and the N end of the alternating current is connected between the third rectifier diode D3 and the fourth rectifier diode D4. The midpoints of the two branches are also connected in series with the N end and the L end of the alternating current. The first resistor R1 and the second resistor R2 have equal resistance values. The positive and negative poles of the rectifier module are connected to the pins of the photoelectric coupler.

[0024] The photocoupler module includes a photocoupler and a pull-up voltage source. The photocoupler has 4 pins, namely pin 1, pin 2, pin 3 and pin 4. Pin 1 is the anode of the LED (light-emitting diode), pin 2 is the cathode of the LED, pin 3 is the emitter of the photodetector, and pin 4 is the collector of the photodetector. Pin 1 is connected to the negative terminal of the rectifier module, and a third resistor R3 is connected in series between pin 1 and the negative terminal, pin 2 is connected to the positive terminal of the rectifier module, pin 3 is grounded, and pin 4 is connected to the pull-up voltage source and the detet detection terminal. The pull-up voltage source includes a pull-up resistor R4, a filter capacitor C, and a 5V power supply connected to the other end of the pull-up resistor. The detet detection terminal is connected to the MCU.

[0025] The working principle of the detection circuit is described in detail below: When AC power is input, if the L terminal is at a high potential and the N terminal is at a low potential, the current loop is R1→D1→R3→pin 1→pin 2→D4→R2, otherwise it is R2→D3→R3→pin 1→pin 2→D2→R1. The output polarity of the AC voltage after rectification in the positive and negative half cycles is the same, so that the photocoupler remains in the on state and the MCU receives a low level; when the AC voltage is zero, the photocoupler will be cut off and the MCU receives a high level. Therefore, the detection circuit can quickly determine the zero-crossing moment of the AC input voltage of the AC PTC heater and feed back the information to the MCU to achieve precise control of the AC PTC heater.

[0026] Those skilled in the art should understand that the present invention can be implemented in many other specific forms without departing from the spirit and scope of the present invention, and all other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

Claims

1. A zero-crossing detection circuit for an AC PTC heater, characterized in that: It includes a photoelectric coupler module and a rectifier module, wherein the rectifier module includes a plurality of rectifier diodes, and the photoelectric coupler module includes a photoelectric coupler and a pull-up voltage source; The first rectifier diode and the second rectifier diode are connected in series to form a first branch, the third rectifier diode and the fourth rectifier diode are connected in series to form a second branch, the first branch and the second branch are connected in parallel to form the rectifier module, the negative terminal of the rectifier module is connected to the LED anode pin of the photoelectric coupler, and the positive terminal of the rectifier module is connected to the LED cathode pin of the photoelectric coupler; The midpoint of the first branch is connected to the L end of the alternating current, and the midpoint of the second branch is connected to the N end of the alternating current.

2. The zero-crossing detection circuit of the AC PTC heater according to claim 1, characterized in that: It also includes a first resistor between the midpoint of the first branch and the AC port, and a second resistor between the midpoint of the second branch and the AC port, and the resistance values ​​of the first resistor and the second resistor are equal.

3. The zero-crossing detection circuit of the AC PTC heater according to claim 1, characterized in that: A third resistor is also included between the negative terminal of the rectifier module and the LED anode pin of the photocoupler.

4. The zero-crossing detection circuit of the AC PTC heater according to claim 1, characterized in that: The photocoupler also has a photodetector emitter pin and a photodetector collector pin, the photodetector emitter pin is grounded, and the photodetector collector pin is connected to a pull-up voltage source and a detect terminal.

5. The zero-crossing detection circuit of the AC PTC heater according to claim 4, characterized in that: The pull-up voltage source includes a pull-up resistor, a filter capacitor, and a 5V power supply connected to the other end of the pull-up resistor.

6. The zero-crossing detection circuit of the AC PTC heater according to claim 4, characterized in that: The detect terminal is connected to the MCU.

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