A multi-stage pulse switching voltage stabilization circuit and voltage stabilization method

Abstract

The present invention discloses a multi-stage pulse switching voltage stabilization circuit and a voltage stabilization method. The primary-side current sampling circuit of the multi-stage pulse switching voltage stabilization circuit collects the current of the voltage regulating circuit, and the secondary-side current sampling circuit and the secondary-side voltage sampling circuit collect the current of the rectifier filter circuit and the output load voltage respectively, and transmit the collected rectifier filter circuit current and the output load voltage to the primary side through the wireless communication module; the control module generates a voltage regulating circuit pulse control signal according to the voltage regulating circuit current, the rectifier filter circuit current transmitted to the primary side, and the output load voltage. The present invention does not add additional equipment to the main circuit and will not affect the power transmission of the main circuit; by applying wide and narrow pulses to the voltage regulating circuit, the control method is simple, and no complicated programming settings are required, so that good voltage stabilization output can be achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless power transmission, and in particular to a multi-stage pulse switching voltage stabilization circuit and a voltage stabilization method. Background Art

[0002] Traditional power transmission is mainly through point-to-point metal wires, which belongs to direct contact transmission. This transmission method uses cables as a medium, and some problems are inevitable in the process of power transmission. For example, electric sparks caused by factors such as tip discharge and line aging will not only increase line losses, but also greatly reduce the reliability and safety of power supply, and shorten the life of equipment. In oil fields, drilling and mining wells and other occasions, the traditional power transmission method is prone to produce tiny electric sparks due to friction, and in severe cases, it may even cause explosions and major accidents. Underwater, there is also the risk of electric shock when the wires directly contact the power supply. Wireless power transmission, also known as wireless power transmission or non-contact power transmission, refers to the transmission method of converting electrical energy into other forms of relay energy (such as electromagnetic field energy, laser, microwave and mechanical waves, etc.) through a transmitter, transmitting it over a certain distance, and then converting the relay energy into electrical energy through a receiver to achieve wireless power transmission.

[0003] In actual wireless power transmission applications, input voltage and output load often fluctuate. In order to maintain the normal operation of the system, some methods are usually needed to stabilize the voltage. The current voltage stabilization methods of wireless power transmission devices are usually more complicated and require additional hardware circuits. At the same time, they have the disadvantages of limited anti-interference performance and insufficient real-time performance. Summary of the invention

[0004] In view of the shortcomings of the voltage stabilization method of the existing wireless power transmission device, the present invention proposes a multi-level pulse switching voltage stabilization circuit and a voltage stabilization method.

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

[0006] A multi-stage pulse switching voltage stabilization circuit, characterized in that it includes an input power supply, a voltage regulating circuit, a high-frequency inverter circuit, a resonant coupling circuit, a rectifier filter circuit, an output load, a primary side current sampling circuit, a secondary side current sampling circuit, a secondary side voltage sampling circuit, a wireless communication module, and a control module;

[0007] The input power supply provides DC voltage to the system;

[0008] The voltage regulating circuit regulates the DC voltage of the input power supply and inputs the regulated DC voltage to the high-frequency inverter circuit;

[0009] The high-frequency inverter circuit inverts the DC power into high-frequency AC power, and inputs the high-frequency AC power into the primary side of the resonant coupling circuit;

[0010] The resonant coupling circuit transmits the primary side electric energy to the secondary side through the high-frequency electromagnetic field, and the secondary side inputs the electric energy to the rectifier and filter circuit;

[0011] The rectifier and filter circuit converts high-frequency AC power into DC power and transmits the DC power to the output load;

[0012] The primary side current sampling circuit collects the voltage regulating circuit current, the secondary side current sampling circuit and the secondary side voltage sampling circuit collect the rectifier filter circuit current and the output load voltage respectively, and transmits the collected rectifier filter circuit current and the output load voltage to the primary side through the wireless communication module;

[0013] The control module generates a voltage regulation circuit pulse control signal according to the voltage regulation circuit current, the rectifier filter circuit current transmitted to the primary side, and the output load voltage.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] The present invention transmits the rectifier filter circuit current and output load voltage collected on the secondary side to the primary side through a wireless communication module. The control module generates control variables by summing the voltage regulation circuit current, the rectifier filter circuit current transmitted to the primary side, and the output load voltage according to a certain proportional coefficient, and compares the control variable with the output voltage reference value to determine the frequency and duty cycle of the pulse control signal. The present invention adopts multi-level pulse switching technology, with high control accuracy and small steady-state error; the system has good grid regulation rate and load regulation rate, selects multi-level frequency pulse control, and the system response speed is proportional to the deviation from the steady-state value amplitude; no additional equipment is added to the main circuit, which will not affect the main circuit power transmission; by applying wide and narrow pulses to the voltage regulation circuit, the control method is simple, and no complex programming settings are required to achieve good voltage stabilization output. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 This is a schematic diagram of the mechanism of low-frequency output oscillation generation using pulse switching technology;

[0018] Figure 2 It is a connection topology diagram of a multi-stage pulse switching voltage stabilization circuit;

[0019] Figure 3 The present invention is a flow chart of the voltage stabilization method of a multi-stage pulse switching voltage stabilization circuit. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] According to circuit theory, the factors that affect the output voltage change of the resonant coupling circuit include input voltage, the coupling degree of the coil, and the output load. In actual system operation, there are usually changes in the output load, changes in the coupling degree caused by changes in the coil distance, etc., which cause changes in the output voltage of the resonant coupling circuit. In order to maintain a constant output voltage, you can choose to adjust the input voltage to achieve a regulated output.

[0022] like Figure 1 As shown, when the ordinary pulse switching technology controls the circuit, the output voltage u 0 Waveform and voltage regulation circuit diode current i D There is a phase difference in the waveform, which causes a delay in the control of the system, and it is impossible to achieve that the output voltage rises when the pulse is high and the output voltage drops when the pulse is low. As shown in point A in the figure, the output voltage u 0 Greater than the output reference value V ref , the circuit selects low pulse, but the diode current i D Still greater than the output capacitor current i of the voltage regulator circuit C1 , so the output voltage change trend is still rising, away from the output reference value V ref In this case, output oscillation occurs. The present application uses a control module to sum the primary current sampling signal, the secondary current sampling signal, and the voltage sampling signal according to a certain proportional coefficient to obtain a control variable a. The control variable a is proportional to the diode current i D The phase difference is very small, which eliminates output oscillation and improves the system voltage regulation performance.

[0023] like Figure 2As shown, a multi-stage pulse switching voltage stabilization circuit includes an input power supply, a voltage regulating circuit, a high-frequency inverter circuit, a resonant coupling circuit, a rectifier filter circuit, an output load, a primary-side current sampling circuit, a secondary-side current sampling circuit, a secondary-side voltage sampling circuit, a wireless communication module, and a control module. The input power supply provides a DC voltage for the system. The voltage regulating circuit regulates the DC voltage of the input power supply and inputs the regulated DC voltage to the high-frequency inverter circuit. The high-frequency inverter circuit inverts the DC power into high-frequency AC power and inputs the high-frequency AC power into the primary side of the resonant coupling circuit. The resonant coupling circuit transmits the primary side power to the secondary side through a high-frequency electromagnetic field, and the secondary side is input into the rectifier filter circuit. The rectifier filter circuit converts the high-frequency AC power into DC power and transmits the DC power to the output load. The primary-side current sampling circuit collects the current of the voltage regulating circuit, and the secondary-side current sampling circuit and the secondary-side voltage sampling circuit collect the current of the rectifier filter circuit and the output load voltage respectively, and transmits the collected current of the rectifier filter circuit and the output load voltage to the primary side through the wireless communication module. The control module generates a voltage regulation circuit pulse control signal according to the voltage regulation circuit current, the rectifier filter circuit current transmitted to the primary side, and the output load voltage.

[0024] The voltage regulating circuit includes an input capacitor C1, an N-channel MOSFET Q1, a magnetic ring inductor L1, an output capacitor C2, and a fast recovery diode VD1. The input capacitor C1 is connected in parallel at both ends of the input power supply Vin, and plays the role of filtering the input power supply Vin and absorbing the MOSFET pulsating current. The drain of the N-channel MOSFET Q1 is connected to the input capacitor C1, and the source of the N-channel MOSFET Q1 is connected to the first end of the magnetic ring inductor L1. When the MOSFET Q1 is turned on, the input power supply Vin charges the magnetic ring inductor L1. When the MOSFET Q1 is turned off, the magnetic ring inductor L1 outputs the stored electric energy. The cathode of the fast recovery diode VD1 is connected to the source of the N-channel MOSFET Q1 and the first end of the magnetic ring inductor L1, respectively. The anode of the fast recovery diode VD1 is connected to the cathode of the output capacitor C2. When the MOSFET Q1 is turned off, the fast recovery diode VD1 provides a freewheeling circuit for the magnetic ring inductor L1. The second end of the magnetic ring inductor L1 and the anode of the output capacitor C2 are connected to the cathode of the power supply Vin, respectively, and play the role of output filtering. The output voltage formula of the voltage regulator circuit is as follows:

[0025]

[0026] Among them, V in is the input voltage of the voltage regulator circuit, V o is the output voltage of the voltage regulating circuit, and D is the duty cycle of the control pulse of the voltage regulating circuit.

[0027] The high-frequency inverter circuit includes a bridge circuit composed of four N-channel MOSFETs Q2, Q3, Q4, and Q5. The drain of Q2 is connected to the positive electrode of the fast recovery diode VD1 and the drain of Q4, respectively. The source of Q2 is connected to the drain of Q3, the source of Q4 is connected to the drain of Q5, and the source of Q3 and the source of Q5 are connected to the negative electrode of the power supply Vin. When the high-frequency inverter circuit is working, Q2 and Q5 are turned on at the same time, Q3 and Q4 are turned on at the same time, and the two groups of MOSFETs are turned on alternately. The DC output of the voltage regulation circuit is inverted into high-frequency AC through the high-frequency inverter circuit.

[0028] The resonant coupling circuit includes a primary resonant capacitor C3, a secondary resonant capacitor C4, a primary coupling inductor L2, and a secondary coupling inductor L3. The first end of the primary resonant capacitor C3 is connected between the source of Q2 and the drain of Q3, the second end of the primary resonant capacitor C3 is connected to the first end of the primary coupling inductor L2, and the second end of the primary coupling inductor L2 is connected between the source of Q4 and the drain of Q5; the first end of the secondary resonant capacitor C4 is connected to the first end of the secondary coupling inductor L3, and the second end of the secondary resonant capacitor C4 and the second end of the secondary coupling inductor L3 are respectively connected to the rectifier filter circuit. The primary and secondary resonant capacitors are both high-voltage film capacitors with good high-frequency performance, and the primary and secondary coupling inductors are wound by multiple strands of Litz wire. The high-frequency alternating current output by the high-frequency inverter circuit passes through the resonant coupling circuit, and the coupling inductor induces a high-frequency electromagnetic field, and the electric energy is wirelessly transmitted through the high-frequency electromagnetic field.

[0029] The rectifier and filter circuit includes a bridge circuit composed of four diodes D1, D2, D3, and D4 and a filter capacitor C5. The negative electrode of D1 is connected to the negative electrode of D3, the positive electrode of D2 is connected to the positive electrode of D4, the positive electrode of D1 is connected to the negative electrode of D2, the positive electrode of D3 is connected to the negative electrode of D4, the second end of the secondary resonant capacitor C4 is connected between the positive electrode of D3 and the negative electrode of D4, the second end of the secondary coupling inductor L3 is connected between the positive electrode of D1 and the negative electrode of D2, the first end of the filter capacitor C5 is respectively connected to the negative electrode of D1 and the negative electrode of D3, and the second end of the filter capacitor C5 is respectively connected to the positive electrode of D2 and the positive electrode of D4. The high-frequency alternating current obtained by wireless transmission from the resonant coupling circuit is converted into direct current through the rectifier and filter circuit. The output load R3 is connected in parallel at both ends of the filter capacitor C5.

[0030] The primary current sampling circuit includes a first current transformer, the primary side of which is connected in series between the positive electrode of the output capacitor C2 and the negative electrode of the power supply Vin, and the secondary side of which is connected to the input end of the control module. The primary current sampling circuit samples the current of the branch where the output capacitor C2 is located.

[0031] The secondary current sampling circuit includes a second current transformer, the primary side of which is connected in series between the second end of the filter capacitor C5 and the positive electrode of D4, and the secondary side of which is connected to the input end of the control module through the wireless communication module. The secondary current sampling circuit samples the current of the branch where the filter capacitor C5 is located.

[0032] The secondary side voltage sampling circuit includes a first resistor R1, a second resistor R2, and a voltage follower. The first resistor R1 and the second resistor R2 are connected in series between the two ends of the output load R3. The input end of the voltage follower is connected between the first resistor R1 and the second resistor R2. The output end of the voltage follower is connected to the input end of the control module through a wireless communication module. The wireless communication module selects the NRF24L01 wireless communication module. The secondary side voltage sampling circuit samples the voltage across the second resistor R2.

[0033] like Figure 3 As shown, the present invention also provides a method for voltage stabilization by a multi-stage pulse switching voltage stabilization circuit:

[0034] S1: The primary-side current sampling circuit samples the current of the branch where the output capacitor C2 is located, the secondary-side current sampling circuit samples the current of the branch where the filter capacitor C5 is located, and the secondary-side voltage sampling circuit samples the voltage across the second resistor R2;

[0035] S2: The primary side current sampling signal is transmitted to the control module, and the secondary side current sampling signal and voltage sampling signal are transmitted to the control module through the wireless communication module. The wireless communication module uses the NRF24L01 module, which can realize 2.4GHz electromagnetic wave communication. The secondary side is the wireless communication sending module, and the primary side is the wireless communication receiving module. The control module selects the STM32 series of single-chip microcomputer chips. The control module sums the three sampling signals according to a certain proportional coefficient to obtain the control variable a, that is:

[0036] a=u o +αi c1 +βi c2

[0037] Among them, u o is the system secondary side voltage sampling signal, i c1 is the primary side current sampling signal, i c2 is the secondary side current sampling signal, α and β are both proportional coefficients;

[0038] S3: The control module compares the control variable a with the output voltage reference value V ref Compare and determine the frequency and duty cycle of the pulse control signal:

[0039] When a∈(0, 0.7V ref], pulse 1 is sent, the pulse control signal frequency is 50kHz, the duty cycle is 0.7, and the output voltage rises rapidly;

[0040] When a∈(0.7V ref , V ref ], pulse 2 is sent, the pulse control signal frequency is 30kHz, the duty cycle is 0.6, and the output voltage gradually increases;

[0041] When a∈(V ref , 1.3V ref ], pulse 3 is sent, the pulse control signal frequency is 30kHz, the duty cycle is 0.4, and the output voltage gradually decreases;

[0042] When a∈(1.3V ref , +∞), pulse 4 is sent, the pulse control signal frequency is 50kHz, the duty cycle is 0.3, and the output voltage drops rapidly.

[0043] The control module outputs the corresponding pulse according to the size of the input variable a to complete this control. If the system continues to run, after this control ends, the control module will perform the next control according to the same process. Under specific working conditions, the system output is stable. The control module uses the modulation period as a unit to cyclically output a fixed number of pulses. Different working conditions correspond to different pulse series. Multi-level pulse switching technology requires that the modulation period is less than the switching period of the voltage regulation circuit, so that good voltage stabilization performance can be achieved.

[0044] The present invention transmits the rectifier filter circuit current and output load voltage collected on the secondary side to the primary side through a wireless communication module. The control module generates a control variable by summing the voltage regulation circuit current, the rectifier filter circuit current transmitted to the primary side, and the output load voltage according to a certain proportional coefficient, and compares the control variable with the output voltage reference value to determine the frequency and duty cycle of the pulse control signal. The present invention adopts multi-level pulse switching technology, with high control accuracy and small steady-state error; the system has good grid regulation rate and load regulation rate, selects multi-level frequency pulse control, and the system response speed is proportional to the deviation from the steady-state value amplitude; no additional equipment is added to the main circuit, which will not affect the main circuit power transmission; by applying wide and narrow pulses to the voltage regulation circuit, the control method is simple, and no complex programming settings are required to achieve good voltage stabilization output.

Claims

1. A method for voltage stabilization using a multi-stage pulse switching voltage stabilization circuit, characterized in that: S1: The primary-side current sampling circuit samples the current of the branch where the output capacitor C2 is located, the secondary-side current sampling circuit samples the current of the branch where the filter capacitor C5 is located, and the secondary-side voltage sampling circuit samples the voltage across the second resistor R2; S2: The primary side current sampling signal is transmitted to the control module, and the secondary side current sampling signal and voltage sampling signal are transmitted to the control module through the wireless communication module. The control module sums the three sampling signals according to a certain proportional coefficient to obtain the control variable a, that is: a=u o +αi c1 +βi c2 Among them, u o is the system secondary side voltage sampling signal, i c1 is the primary side current sampling signal, i c2 is the secondary side current sampling signal, α and β are both proportional coefficients; S3: The control module compares the control variable a with the output voltage reference value V ref Compare and determine the frequency and duty cycle of the pulse control signal: When a∈(0, 0.7V ref ], pulse 1 is sent, the pulse control signal frequency is 50kHz, and the duty cycle is 0.7; When a∈(0.7V ref , V ref ], pulse 2 is sent, the pulse control signal frequency is 30kHz, and the duty cycle is 0.6; When a∈(V ref , 1.3V ref ], pulse 3 is sent, the pulse control signal frequency is 30kHz, and the duty cycle is 0.4; When a∈(1.3V ref , +∞), pulse 4 is sent, the pulse control signal frequency is 50kHz, and the duty cycle is 0.3; The multi-stage pulse switching voltage stabilization circuit includes an input power supply, a voltage regulation circuit, a high-frequency inverter circuit, a resonant coupling circuit, a rectifier filter circuit, an output load, a primary side current sampling circuit, a secondary side current sampling circuit, a secondary side voltage sampling circuit, a wireless communication module, and a control module; The input power supply provides a DC voltage to the system; The voltage regulating circuit regulates the DC voltage of the input power supply and inputs the regulated DC voltage to the high-frequency inverter circuit; The high-frequency inverter circuit inverts the DC power into high-frequency AC power, and inputs the high-frequency AC power into the primary side of the resonant coupling circuit; The resonant coupling circuit transmits the primary side electric energy to the secondary side through a high-frequency electromagnetic field, and the secondary side inputs the electric energy to the rectifier and filter circuit; The rectifier and filter circuit converts high-frequency AC power into DC power and transmits the DC power to the output load; The primary side current sampling circuit collects the voltage regulating circuit current, and the secondary side current sampling circuit and the secondary side voltage sampling circuit collect the rectifier filter circuit current and the output load voltage respectively, and transmit the collected rectifier filter circuit current and the output load voltage to the primary side through the wireless communication module; The control module generates a voltage regulation circuit pulse control signal according to the voltage regulation circuit current, the rectifier filter circuit current transmitted to the primary side, and the output load voltage.

2. The method for voltage stabilization using a multi-stage pulse switching voltage stabilization circuit according to claim 1, characterized in that: The voltage regulating circuit includes an input capacitor C1, an N-channel MOSFET Q1, a magnetic ring inductor L1, an output capacitor C2, and a fast recovery diode VD1. The input capacitor C1 is connected in parallel at both ends of an input power supply Vin. The drain of the N-channel MOSFET Q1 is connected to the input capacitor C1, the source of the N-channel MOSFET Q1 is connected to the first end of the magnetic ring inductor L1, the cathode of the fast recovery diode VD1 is respectively connected to the source of the N-channel MOSFET Q1 and the first end of the magnetic ring inductor L1, the anode of the fast recovery diode VD1 is connected to the cathode of the output capacitor C2, and the second end of the magnetic ring inductor L1 and the anode of the output capacitor C2 are respectively connected to the cathode of the power supply Vin.

3. The method for voltage stabilization using a multi-stage pulse switching voltage stabilization circuit according to claim 2, characterized in that: The high-frequency inverter circuit includes a bridge circuit composed of four N-channel MOSFETs Q2, Q3, Q4, and Q5, wherein the drain of Q2 is connected to the positive electrode of the fast recovery diode VD1 and the drain of Q4 respectively, the source of Q2 is connected to the drain of Q3, the source of Q4 is connected to the drain of Q5, and the source of Q3 and the source of Q5 are connected to the negative electrode of the power supply Vin respectively.

4. The method for voltage stabilization using a multi-stage pulse switching voltage stabilization circuit according to claim 3, characterized in that: The resonant coupling circuit includes a primary resonant capacitor C3, a secondary resonant capacitor C4, a primary coupling inductor L2, and a secondary coupling inductor L3. The first end of the primary resonant capacitor C3 is connected between the source of Q2 and the drain of Q3, the second end of the primary resonant capacitor C3 is connected to the first end of the primary coupling inductor L2, and the second end of the primary coupling inductor L2 is connected between the source of Q4 and the drain of Q5; the first end of the secondary resonant capacitor C4 is connected to the first end of the secondary coupling inductor L3, and the second end of the secondary resonant capacitor C4 and the second end of the secondary coupling inductor L3 are respectively connected to the rectifier and filter circuit.

5. The method for voltage stabilization using a multi-stage pulse switching voltage stabilization circuit according to claim 4, characterized in that: The rectifier and filter circuit includes a bridge circuit composed of four diodes D1, D2, D3, and D4 and a filter capacitor C5, wherein the negative electrode of D1 is connected to the negative electrode of D3, the positive electrode of D2 is connected to the positive electrode of D4, the positive electrode of D1 is connected to the negative electrode of D2, the positive electrode of D3 is connected to the negative electrode of D4, the second end of the secondary resonant capacitor C4 is connected between the positive electrode of D3 and the negative electrode of D4, the second end of the secondary coupling inductor L3 is connected between the positive electrode of D1 and the negative electrode of D2, the first end of the filter capacitor C5 is respectively connected to the negative electrode of D1 and the negative electrode of D3, and the second end of the filter capacitor C5 is respectively connected to the positive electrode of D2 and the positive electrode of D4.

6. The method for voltage stabilization using a multi-stage pulse switching voltage stabilization circuit according to claim 5, characterized in that: The output load R3 is connected in parallel across the filter capacitor C5.

7. The method for voltage stabilization using a multi-stage pulse switching voltage stabilization circuit according to claim 6, characterized in that: The primary-side current sampling circuit includes a first current transformer, a primary side of the first current transformer is connected in series between the positive electrode of the output capacitor C2 and the negative electrode of the power supply Vin, and a secondary side of the first current transformer is connected to an input end of the control module.

8. The method for voltage stabilization using a multi-stage pulse switching voltage stabilization circuit according to claim 7, characterized in that: The secondary current sampling circuit includes a second current transformer, the primary side of which is connected in series between the second end of the filter capacitor C5 and the positive electrode of D4, and the secondary side of which is connected to the input end of the control module through the wireless communication module.

9. The method for voltage stabilization using a multi-stage pulse switching voltage stabilization circuit according to claim 8, characterized in that: The secondary side voltage sampling circuit includes a first resistor R1, a second resistor R2, and a voltage follower. The first resistor R1 and the second resistor R2 are connected in series between the two ends of the output load R3. The input end of the voltage follower is connected between the first resistor R1 and the second resistor R2. The output end of the voltage follower is connected to the input end of the control module through a wireless communication module.

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