A new wireless charging circuit based on UC2845

Abstract

The invention discloses a novel wireless charging circuit based on UC2845, comprising a rectifier and filter circuit, a transmitter circuit and a receiver circuit. The rectifier and filter circuit is used to convert alternating current into direct current, the transmitter circuit is used to convert the direct current output by the rectifier and filter circuit into a high-frequency oscillation power supply, and the receiver circuit is used to convert the high-frequency oscillation power supply output by the transmitter circuit into direct current. In view of the problem that there is little research in the field of wireless charging with small and medium powers of tens to hundreds of watts in the prior art and the technology is immature, the invention provides a novel wireless charging circuit based on UC2845, which is suitable for wireless charging with small and medium powers of tens to hundreds of watts.

Description

Technical Field

[0001] The invention belongs to the field of wireless charging, and in particular relates to a novel wireless charging circuit based on UC2845. Background Art

[0002] Wireless Power Transfer (WPT), as the name implies, refers to a method of energy transmission from the power supply to the power load without direct electrical contact, without the help of transmission wires, through electromagnetic fields, electromagnetic waves and other energy transmission media in physical space. The development of wireless power transmission technology will greatly change the way people use electricity in production and life. Without the constraints of cables and wires, people will be more convenient in the process of using electricity. From a practical point of view, wireless power transmission technology can get rid of the inconvenience of wired power supply and realize flexible power supply for electrical equipment in daily life; from a safety point of view, wireless power transmission technology reduces safety hazards such as aging of wires and sparks generated by contact friction, and avoids safety accidents caused by leakage and discharge.

[0003] At present, the research on wireless charging is mainly concentrated in two directions, one is the field of mobile phone wireless chargers, the power level is generally 5-20W, and the other is the field of electric vehicle wireless charging, the power level is from several kilowatts to tens or even hundreds of kilowatts, while the research in the field of small and medium power wireless charging of tens to hundreds of watts between the two is less, the technology is not mature, and this field also has broad application prospects in the future. For example, with the large and widespread application of drones, in the field of wireless charging of drones, small and medium power wireless charging will have broad application prospects; for example, in the field of electric bicycles, with the introduction of national standards, electric bicycles have legal status, and there are huge safety risks in the wired charging of electric bicycles. Therefore, wireless charging of electric bicycles may also become a trend in the future. Summary of the invention

[0004] In view of the problem that there is little research in the field of wireless charging with small and medium powers of tens to hundreds of watts in the prior art and the technology is immature, the present invention provides a novel wireless charging circuit based on UC2845, which is suitable for wireless charging with small and medium powers of tens to hundreds of watts.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A novel wireless charging circuit based on UC2845, including a rectifier and filter circuit, a transmitter circuit and a receiver circuit;

[0007] The rectifier and filter circuit is used to convert the input alternating current into direct current;

[0008] The transmitting end circuit includes a main power circuit and a control circuit, which are used to convert the direct current output by the rectifying and filtering circuit into a high-frequency oscillating power supply;

[0009] The main power circuit includes a capacitor C2, a resistor R2, a diode D5, a coil 1, a MOS tube Q1 and a current sampling resistor R8; the capacitor C2, the resistor R2 and the diode D5 constitute an absorption circuit, the input end of which is connected to the output end of the rectifier filter circuit, and the output end is connected to the coil 1, and the coil 1 is a primary coil; the MOS tube Q1 is used for switching, and the current sampling resistor R8 is used for sampling current signals and converting the current signals into voltage signals;

[0010] The control circuit includes a UC2845 chip, a resistor R1, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a capacitor C3, a capacitor C4, a capacitor C5, a capacitor C6, a capacitor C7, a diode D6, and a coil 2; Pin 1 of the UC2845 chip is the output end of an internal operational amplifier and is grounded through a capacitor C6; Pin 2 of the UC2845 chip is grounded through a resistor R3 to form a non-feedback circuit; Pin 3 of the UC2845 chip and R8, R6, and C7 form a current sampling circuit, and Pin 3 is a current monitoring pin. The voltage signal output by the resistor R8 passes through a filter circuit formed by the resistor R6 and the capacitor C7 and is input to Pin 3 for overcurrent or short circuit protection; Pins 4 and 8 of the UC2845 chip and C4, R4, and C5 form an oscillator Circuit, the resistor R4, the capacitor C5 and the 4th pin of the UC2845 chip form an oscillation network for making the UC2845 chip generate a PWM wave, the 8th pin of the UC2845 chip is a 5V reference voltage output terminal, which is used to provide an oscillation voltage source for the 4th pin; the 5th pin of the UC2845 chip is grounded; the 6th pin of the UC2845 chip is a PWM output pin, and forms a MOS tube drive circuit with R5 and R7; one end of the resistor R1 is connected to the output end of the rectifier and filter circuit, and the other end is connected to the 7th pin VCC of the UC2845 chip, which is used to provide a starting voltage for the 7th pin VCC of the UC2845 chip and limit the starting current, the diode D6, the capacitor C3 and the coil 2 form a DC voltage stabilizing circuit, which is used to power the UC2845 chip after startup;

[0011] The receiving end circuit includes more than one receiving end, and the receiving end is used to convert the high-frequency oscillation power output by the transmitting end circuit into direct current;

[0012] The receiving end includes a secondary coil, a rectifier diode, a filter capacitor 1, a BUCK circuit, a filter capacitor 2 and a resistor R0. The rectifier diode and the filter capacitor 1 constitute a half-wave rectifier filter circuit, the input end is connected to the secondary coil, the output end is connected to the BUCK circuit input end, and the BUCK circuit output end is connected to the input end of the filter circuit constituted by the filter capacitor 2 and the resistor R0.

[0013] Further improvement of the technical solution of the present invention, the rectifier filter circuit includes a diode D1, a diode D2, a diode D3, a diode D4 and a filter capacitor C1, the diode D1, the diode D2, the diode D3 and the diode D4 are connected as a single-phase bridge rectifier circuit, and the output end is connected to the filter capacitor C1. The rectifier filter circuit is composed of four diodes and a filter capacitor, which can convert the input 220V AC of the mains into DC as the DC input of the subsequent circuit.

[0014] A further improvement to the technical solution of the present invention is that the receiving end circuit includes a receiving end 1, a receiving end 2 and a receiving end 3; the receiving end 1 includes a coil 3, a rectifier diode D7, a filter capacitor C8, a BUCK circuit, a filter capacitor C9 and a resistor R0; the rectifier diode D7 and the filter capacitor C8 constitute a half-wave rectifier filter circuit, the input end of which is connected to the coil 3, the output end of which is connected to the BUCK circuit input end, and the output end of the BUCK circuit is connected to the input end of the filter circuit constituted by the filter capacitor C9 and the resistor R0; the receiving end 2 includes a coil 4, a rectifier diode D8, a filter capacitor C10, a BUCK circuit, a filter capacitor C11 and a resistor R0; the rectifier diode D8 and the filter The wave capacitor C10 constitutes a half-wave rectifier filter circuit, the input end is connected to the coil 4, the output end is connected to the BUCK circuit input end, and the BUCK circuit output end is connected to the input end of the filter circuit composed of the filter capacitor C11 and the resistor R0; the receiving end three includes the coil 5, the rectifier diode D9, the filter capacitor C12, the BUCK circuit, the filter capacitor C13 and the resistor R0; the rectifier diode D9 and the filter capacitor C12 constitute a half-wave rectifier filter circuit, the input end is connected to the coil 5, the output end is connected to the BUCK circuit input end, and the BUCK circuit output end is connected to the input end of the filter circuit composed of the filter capacitor C13 and the resistor R0; the coil 3, the coil 4, and the coil 5 are secondary coils. Setting three receiving ends can realize one-to-three wireless charging.

[0015] Compared with the prior art, the technical effects of the present invention are:

[0016] 1. The circuit of the present invention is designed based on the UC2845 chip and is suitable for wireless charging with small and medium power ranging from tens to hundreds of watts.

[0017] 2. The circuit described in the present invention is derived from a flyback circuit, has a simple circuit structure, does not require complex control, and reduces the difficulty of large-scale manufacturing and use. At the same time, the entire control circuit in the present invention is based on the UC2845 chip. The UC2845 chip is a current mode PWM controller, which is mostly used in the field of flyback power supplies. It is a very mature and widely used chip with excellent performance.

[0018] 3. The circuit of the present invention uses conventional devices with low cost. For example, the core control chip UC2845 of the circuit costs only 1 to 2 yuan. Together with other components, the estimated batch cost is only tens of yuan, which is suitable for large-scale commercial promotion.

[0019] 4. The circuit of the present invention is provided with more than one receiving end, which can realize "one-to-many" charging, that is, one charging device can simultaneously meet the wireless charging needs of multiple electrical devices.

[0020] 5. In the circuit described in the present invention, the voltage received by the receiving end is unstable due to the influence of factors such as coil spacing and lateral offset, resulting in unstable output voltage. The BUCK circuit is a step-down chopper circuit known in the art, which can convert this unstable DC voltage into a stable DC output voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is an overall structural diagram of an embodiment of the present invention.

[0022] Figure 2 It is a circuit diagram of a rectifier and filter circuit, a transmitter circuit and a receiver circuit according to an embodiment of the present invention.

[0023] Figure 3 It is a circuit diagram of a BUCK circuit in a receiving end 1 of an embodiment of the present invention. DETAILED DESCRIPTION

[0024] The present invention will be further described below in conjunction with the accompanying drawings and specific implementation methods.

[0025] like Figure 1 , 2 As shown, a novel wireless charging circuit based on UC2845 includes a rectifier filter circuit 1, a transmitter circuit 2 and a receiver circuit 3; the rectifier filter circuit 1 is used to convert AC power into DC power, the transmitter circuit 2 is used to convert the DC power output by the rectifier filter circuit into a high-frequency oscillation power supply, and the receiver circuit 3 includes more than one receiving end, and the receiving end is used to convert the high-frequency oscillation power output by the transmitter circuit into DC power;

[0026] The rectifier filter circuit 1 comprises a diode D1, a diode D2, a diode D3, a diode D4 and a filter capacitor C1, wherein the diode D1, the diode D2, the diode D3 and the diode D4 are connected to form a single-phase bridge rectifier circuit, and the output end is connected to the filter capacitor C1;

[0027] The transmitting end circuit 2 includes a main power circuit and a control circuit;

[0028] The main power circuit includes capacitor C2, resistor R2, diode D5, coil 1, MOS tube Q1 and current sampling resistor R8;

[0029] Capacitor C2, resistor R2 and diode D5 form an absorption circuit, the input end of which is connected to the output end of the rectifier filter circuit, and the output end is connected to coil 1, which is the primary coil;

[0030] MOS tube Q1 is used for switching, and current sampling resistor R8 is used for sampling current signals and converting the current signals into voltage signals;

[0031] The control circuit includes a UC2845 chip, a resistor R1, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a capacitor C3, a capacitor C4, a capacitor C5, a capacitor C6, a capacitor C7, a diode D6, and a coil 2;

[0032] Pin 1 of the UC2845 chip is the output of the internal operational amplifier and is grounded through capacitor C6;

[0033] Pin 2 of the UC2845 chip is connected to ground through resistor R3 to form a non-feedback circuit;

[0034] Pin 3 of the UC2845 chip and R8, R6, and C7 form a current sampling circuit. Pin 3 is the current monitoring pin. The voltage signal output by resistor R8 passes through the filter circuit composed of resistor R6 and capacitor C7 and is input to pin 3 for overcurrent or short circuit protection.

[0035] Pin 4 and 8 of UC2845 chip and C4, R4 and C5 form an oscillation circuit. Resistor R4, capacitor C5 and pin 4 of UC2845 chip form an oscillation network, which is used to make UC2845 chip generate PWM wave. Pin 8 of UC2845 chip is the 5V reference voltage output terminal, which is used to provide an oscillation voltage source for pin 4.

[0036] Pin 5 of the UC2845 chip is grounded;

[0037] Pin 6 of UC2845 chip is PWM output pin, and it forms MOS tube driving circuit with R5 and R7;

[0038] One end of the resistor R1 is connected to the output end of the rectifier filter circuit, and the other end is connected to the 7-pin VCC of the UC2845 chip, which is used to provide a startup voltage for the 7-pin VCC of the UC2845 chip and limit the startup current. The diode D6, the capacitor C3 and the coil 2 form a DC voltage stabilizing circuit, which is used to power the UC2845 chip after startup;

[0039] Among them, C2, R2, and D5 form an absorption circuit, which can absorb the peak voltage on the MOS tube. Pin 2 is the voltage feedback terminal. This circuit is an open-loop control and directly outputs a PWM wave with a duty cycle of 50%. This pin is not needed, so it is grounded through resistor R3; the voltage sampled by R8 is input into pin 3 through the filter circuit composed of R6 and C7. In this way, pin 3 can monitor the state of the current in the circuit. When overcurrent or short circuit occurs, it enters the intermittent working state to achieve overcurrent or short circuit protection.

[0040] In this embodiment, the receiving end circuit 3 includes a receiving end 1, a receiving end 2 and a receiving end 3;

[0041] The receiving end 1 includes a coil 3, a rectifier diode D7, a filter capacitor C8, a BUCK circuit, a filter capacitor C9 and a resistor R0; the rectifier diode D7 and the filter capacitor C8 constitute a half-wave rectifier filter circuit, the input end of which is connected to the coil 3, the output end of which is connected to the input end of the BUCK circuit, and the output end of the BUCK circuit is connected to the input end of the filter circuit constituted by the filter capacitor C9 and the resistor R0;

[0042] The receiving end 2 includes a coil 4, a rectifier diode D8, a filter capacitor C10, a BUCK circuit, a filter capacitor C11 and a resistor R0; the rectifier diode D8 and the filter capacitor C10 constitute a half-wave rectifier filter circuit, the input end of which is connected to the coil 4, the output end of which is connected to the input end of the BUCK circuit, and the output end of the BUCK circuit is connected to the input end of the filter circuit constituted by the filter capacitor C11 and the resistor R0;

[0043] The receiving end three includes a coil 5, a rectifier diode D9, a filter capacitor C12, a BUCK circuit, a filter capacitor C13 and a resistor R0; the rectifier diode D9 and the filter capacitor C12 constitute a half-wave rectifier filter circuit, the input end of which is connected to the coil 5, the output end of which is connected to the input end of the BUCK circuit, and the output end of the BUCK circuit is connected to the input end of the filter circuit constituted by the filter capacitor C13 and the resistor R0;

[0044] The coils 3, 4 and 5 are secondary coils;

[0045] like Figure 3 As shown, the input end of the BUCK circuit is connected to the rectifier diode D7 and the filter capacitor C8 to form a half-wave rectifier filter circuit, and the output end is connected to the input end of the filter circuit formed by the filter capacitor C9 and the resistor R0. The BUCK circuit used in the receiving end of this embodiment is a step-down chopper circuit known in the art. Due to the influence of factors such as the coil spacing and the lateral offset, the voltage received by the receiving end is unstable, resulting in an unstable output voltage. The function of the BUCK circuit is to convert this unstable DC voltage into a stable DC output voltage;

[0046] In this embodiment, the BUCK circuits in the second receiving end and the third receiving end have the same structure as the BUCK circuit used in the first receiving end.

[0047] When the novel wireless charging circuit based on UC2845 described in this embodiment is used, the rectifier and filter circuit and the transmitter circuit are arranged in a wireless charging device, the 220V AC power of the mains is connected to the rectifier and filter circuit, and the power input end of the electrical equipment (such as drones, electric bicycles, etc.) that requires small and medium power wireless charging of tens to hundreds of watts is connected to the receiving end circuit, specifically to the output end of the filter circuit in the receiving end circuit, so that the wireless charging device can be used to wirelessly charge these electrical equipment.

Claims

1. A new wireless charging circuit based on UC2845, characterized by: It comprises a rectifying and filtering circuit (1), a transmitting end circuit (2) and a receiving end circuit (3); The rectifier and filter circuit (1) is used to convert input alternating current into direct current; The transmitting end circuit (2) comprises a main power circuit and a control circuit, which are used to convert the direct current output by the rectifying and filtering circuit into a high-frequency oscillating power supply; The main power circuit includes a capacitor C2, a resistor R2, a diode D5, a coil 1, a MOS tube Q1 and a current sampling resistor R8; the capacitor C2, the resistor R2 and the diode D5 constitute an absorption circuit, the input end of which is connected to the output end of the rectifier filter circuit, and the output end is connected to the coil 1, and the coil 1 is a primary coil; the MOS tube Q1 is used for switching, and the current sampling resistor R8 is used for sampling current signals and converting the current signals into voltage signals; The control circuit includes a UC2845 chip, a resistor R1, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a capacitor C3, a capacitor C4, a capacitor C5, a capacitor C6, a capacitor C7, a diode D6, and a coil 2; Pin 1 of the UC2845 chip is the output end of an internal operational amplifier and is grounded through a capacitor C6; Pin 2 of the UC2845 chip is grounded through a resistor R3 to form a non-feedback circuit; Pin 3 of the UC2845 chip and R8, R6, and C7 form a current sampling circuit, and Pin 3 is a current monitoring pin. The voltage signal output by the resistor R8 passes through a filter circuit formed by the resistor R6 and the capacitor C7 and is input to Pin 3 for overcurrent or short circuit protection; Pins 4 and 8 of the UC2845 chip and C4, R4, and C5 form an oscillator Circuit, the resistor R4, the capacitor C5 and the 4th pin of the UC2845 chip form an oscillation network for making the UC2845 chip generate a PWM wave, the 8th pin of the UC2845 chip is a 5V reference voltage output terminal, which is used to provide an oscillation voltage source for the 4th pin; the 5th pin of the UC2845 chip is grounded; the 6th pin of the UC2845 chip is a PWM output pin, and forms a MOS tube drive circuit with R5 and R7; one end of the resistor R1 is connected to the output end of the rectifier and filter circuit, and the other end is connected to the 7th pin VCC of the UC2845 chip, which is used to provide a starting voltage for the 7th pin VCC of the UC2845 chip and limit the starting current, the diode D6, the capacitor C3 and the coil 2 form a DC voltage stabilizing circuit, which is used to power the UC2845 chip after startup; The receiving end circuit (3) comprises one or more receiving ends, and the receiving ends are used to convert the high-frequency oscillating power output by the transmitting end circuit into direct current; The receiving end includes a secondary coil, a rectifier diode, a filter capacitor 1, a BUCK circuit, a filter capacitor 2 and a resistor R0, wherein the rectifier diode and the filter capacitor 1 constitute a half-wave rectifier filter circuit, wherein the input end is connected to the secondary coil, the output end is connected to the BUCK circuit input end, and the BUCK circuit output end is connected to the input end of the filter circuit constituted by the filter capacitor 2 and the resistor R0; The rectifier filter circuit (1) comprises a diode D1, a diode D2, a diode D3, a diode D4 and a filter capacitor C1, wherein the diode D1, the diode D2, the diode D3 and the diode D4 are connected to form a single-phase bridge rectifier circuit, and the output end is connected to the filter capacitor C1; The receiving end circuit (3) comprises a receiving end 1, a receiving end 2 and a receiving end 3; The receiving end 1 includes a coil 3, a rectifier diode D7, a filter capacitor C8, a BUCK circuit, a filter capacitor C9 and a resistor R0; the rectifier diode D7 and the filter capacitor C8 constitute a half-wave rectifier filter circuit, the input end of which is connected to the coil 3, the output end of which is connected to the BUCK circuit input end, and the output end of the BUCK circuit is connected to the input end of the filter circuit constituted by the filter capacitor C9 and the resistor R0; The receiving end 2 includes a coil 4, a rectifier diode D8, a filter capacitor C10, a BUCK circuit, a filter capacitor C11 and a resistor R0; the rectifier diode D8 and the filter capacitor C10 constitute a half-wave rectifier filter circuit, the input end of which is connected to the coil 4, the output end of which is connected to the input end of the BUCK circuit, and the output end of the BUCK circuit is connected to the input end of the filter circuit constituted by the filter capacitor C11 and the resistor R0; The receiving end three includes a coil 5, a rectifier diode D9, a filter capacitor C12, a BUCK circuit, a filter capacitor C13 and a resistor R0; the rectifier diode D9 and the filter capacitor C12 constitute a half-wave rectifier filter circuit, the input end of which is connected to the coil 5, the output end of which is connected to the input end of the BUCK circuit, and the output end of the BUCK circuit is connected to the input end of the filter circuit constituted by the filter capacitor C13 and the resistor R0; The coils 3, 4 and 5 are secondary coils.

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