Isolation transmission-based bidirectional equalization controller and power converter
By replacing optocoupler isolation with transformer magnetic isolation technology, a bidirectional equalization controller based on isolated transmission was designed, which solved the problems of high price and safety requirements of optocoupler isolation devices, and achieved cost reduction and localization.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SUZHOU VERY POWER SEMICONDUCTOR CO LTD
- Filing Date
- 2025-04-22
- Publication Date
- 2026-06-12
AI Technical Summary
In the existing technology, optocoupler isolation devices are expensive, have limited selection, and are difficult to meet safety regulations regarding high isolation withstand voltage and creepage distance, resulting in high cost of bidirectional equalization modules and difficulties in domestic production.
A bidirectional equalization controller based on isolated transmission is designed by replacing optocoupler isolation with transformer magnetic isolation technology and transmitting signals through a transformer. The controller utilizes an oscillation circuit, switching devices, rectifier and filter circuits, and a controllable load to achieve magnetic isolation transmission and uses only one magnetic isolation device for bidirectional equalization control.
This reduced product costs, increased creepage distance, met safety regulations, and promoted the localization of products.
Smart Images
Figure CN120433370B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of battery voltage bidirectional equalization control technology, and in particular to a bidirectional equalization controller and power converter based on isolated transmission. Background Technology
[0002] The battery energy storage industry is developing rapidly and its applications are becoming increasingly widespread. Due to factors such as battery materials and manufacturing processes, the voltage of individual cells within a battery pack can become inconsistent after charging or discharging. This leads to reduced battery pack lifespan and safety issues caused by overcharging and discharging. Since batteries account for over 80% of the total cost, improving battery lifespan is equivalent to significantly reducing costs. Bidirectional battery balancing technology has become a necessary means to improve battery lifespan. Simply put, bidirectional balancing technology involves charging cells with lower voltage and discharging cells with higher voltage, ultimately bringing all individual cells to a consistent operating state. This technology is designed to easily adapt to different application scenarios.
[0003] A commonly used application block diagram for bidirectional equalization is as follows: Figure 1 As shown in the diagram, the main power topology is a flyback power converter. Its forward charging and reverse discharging are controlled by a host computer. Generally, the host computer shares a common ground with the forward PWM controller and is isolated from the reverse PWM controller. When the host computer controls the reverse PWM controller, an isolation device (corresponding to...) is required. Figure 1 For signal transmission, optocoupler OPT1 is used. When the system needs forward charging, the host computer controls the forward PWM controller to work and the reverse PWM controller to work, forming a flyback constant current circuit with left input and right output. The current sampling resistor samples the forward charging current and inputs it to the current error amplifier, then feeds it back to the forward PWM controller through optocoupler OPT2, forming a closed-loop feedback that can precisely control the forward charging current. When the system needs reverse charging, the host computer controls the forward PWM controller to work and the reverse PWM controller to work, forming a flyback constant current circuit with right input and left output. The current sampling resistor samples the reverse discharge current and inputs it to the secondary PWM control circuit, forming a closed-loop feedback that can precisely control the reverse discharge current. For forward constant current charging, the following can be used: Figure 1 The direct sampling of the secondary side charging current shown is a closed-loop control method with high constant current control accuracy.
[0004] As energy storage capacity continues to increase, the voltage of energy storage systems also increases, leading to higher requirements for isolation performance. The isolation withstand voltage of bidirectional balancing modules has gradually increased from 6kVdc to 10kVdc, and the creepage distance from 16mm to 21mm. In this application context, optocouplers have become a technological bottleneck, mainly in the following aspects: 1. Limited selection and high price of high-isolation withstand voltage optocouplers; 2. Creepage distance does not meet safety regulations; 3. There are almost no domestically produced high-isolation withstand voltage optocouplers, relying mainly on foreign brands.
[0005] It should be noted that the information disclosed in the background section is intended only to enhance the understanding of the overall background of this application and should not be construed as an admission or implication in any way that the information is prior art known to those skilled in the art. Summary of the Invention
[0006] The purpose of this invention is to provide a bidirectional equalization controller and power converter based on isolated transmission, which can solve the problems of high price, limited selection, and failure to meet safety requirements caused by sampling optocoupler isolation in the prior art.
[0007] The objective of this invention is achieved through the following technical solution:
[0008] In a first aspect, the present invention provides a bidirectional equalization controller based on isolated transmission, comprising a second transformer T2, an oscillation circuit, a switching device, a forward PWM controller, a rectifier filter circuit, a controllable load, a current error amplifier, and a reverse PWM controller; one end of the primary winding of the second transformer T2 is input to the supply voltage VDD; the input end of the oscillation circuit receives a reverse enable signal sent by a host computer, and the output end is connected to the other end of the primary winding of the second transformer T2 via the switching device; one input end of the forward PWM controller receives a forward enable signal; the input end of the rectifier filter circuit is connected to both ends of the secondary winding of the second transformer T2, and the output end of the rectifier filter circuit is connected to the controllable load. The load input terminal and the inverting PWM controller input terminal are connected. The current error amplifier samples the battery charging current, and after error amplification, outputs a voltage signal VEA to the control terminal of the controllable load. The controllable load extracts a current signal IFB_S, which is monotonically related to the voltage signal VEA, from the output terminal of the rectifier filter circuit. This signal is then isolated and fed back to the primary winding through the secondary winding of the second transformer T2, forming a current feedback signal IFB_P, which is monotonically related to the voltage signal VEA. The current feedback signal IFB_P is converted into a voltage feedback signal VFB_P and input to the other input terminal of the forward PWM controller. The forward PWM controller controls the charging current according to the voltage feedback signal VFB_P.
[0009] Furthermore, the controllable load includes a first transistor Q4 and a third resistor R3; the collector of the first transistor Q4 serves as the input terminal of the controllable load, extracting a current signal IFB_S from the rectifier filter circuit, and the emitter of the first transistor Q4 is grounded; one end of the third resistor R3 serves as the control terminal of the controllable load, inputting a voltage signal VEA, and the other end is connected to the base of the first transistor Q4.
[0010] Furthermore, the controllable load includes a fifth MOSFET Q5, a second operational amplifier OP2, a fifth capacitor C5, and a fourth resistor R4; the drain of the fifth MOSFET Q5 serves as the input terminal of the controllable load, drawing a current signal IFB_S from the rectifier filter circuit, and the source is grounded through the fourth resistor R4; the non-inverting input terminal of the second operational amplifier OP2 serves as the control terminal of the controllable load, inputting a voltage signal VEA, the inverting input terminal is connected to the drain of the fifth MOSFET Q5, and the output terminal is connected to the gate of the fifth MOSFET Q5; the fifth capacitor C5 is connected between the inverting input terminal and the output terminal of the second operational amplifier OP2.
[0011] Furthermore, the current error amplifier includes a first operational amplifier OP1 and a fourth capacitor C4; the non-inverting input of the first operational amplifier OP1 samples the charging current of the battery, the inverting input receives the reference voltage VREF, and the output outputs the voltage signal VEA; the fourth capacitor C4 is connected between the inverting input and the output of the first operational amplifier OP1.
[0012] Furthermore, the switching device is one of a MOSFET, a flyback circuit, a forward circuit, a half-bridge circuit, and a full-bridge circuit.
[0013] Furthermore, the rectifier and filter circuit is one of half-wave rectification, full-wave rectification, or bridge rectification.
[0014] Furthermore, the fifth capacitor C5 can be replaced by a resistor and a capacitor connected in series, or a resistor and a capacitor connected in parallel.
[0015] Furthermore, the fourth capacitor C4 can be replaced by a resistor and a capacitor connected in series, or a resistor and a capacitor connected in parallel.
[0016] Furthermore, the forward PWM controller or reverse PWM controller is one of the following: voltage-type PWM controller, peak current-type PWM controller, average current-type PWM controller, and PFM controller.
[0017] Secondly, the present invention provides a power converter, including a first transformer T1, a first MOSFET Q1, and a second MOSFET Q2, and further including the aforementioned bidirectional equalization controller based on isolated transmission; the drain of the first MOSFET Q1 is connected to one end of the primary winding of the first transformer T1, and the source of the first MOSFET Q1 is connected to the negative terminal of the power supply; the other end of the primary winding of the first transformer T1 is connected to the positive terminal of the power supply; the gate of the first MOSFET Q1 is connected to the output terminal of the positive PWM controller; the drain of the second MOSFET Q2 is connected to one end of the secondary winding of the first transformer T1, and the source of the second MOSFET Q2 is connected to the negative terminal of the battery; the other end of the secondary winding of the first transformer T1 is connected to the positive terminal of the battery; the gate of the second MOSFET Q2 is connected to the output terminal of the reverse PWM controller; and a current error amplifier samples the battery charging current.
[0018] This invention relates to a bidirectional equalization controller and power converter based on isolated transmission. Employing only a single magnetic isolation device, it enables both forward and reverse operation of the bidirectional equalization controller. During forward operation, the secondary battery charging current value can be fed back via magnetic isolation transmission, facilitating timely adjustment of the charging current and ensuring its accuracy. Furthermore, using only one magnetic isolation device instead of the two optocoupler isolation devices in existing technologies reduces product costs and increases creepage distance. This also facilitates product selection and meets safety regulations, thereby promoting the localization of the product. Attached Figure Description
[0019] Figure 1 This is a block diagram illustrating the application of a bidirectional equalizer controller in existing technology.
[0020] Figure 2 This is a circuit block diagram of the bidirectional equalizer controller based on isolated transmission according to the present invention.
[0021] Figure 3 This is one of the circuit schematics for switching devices and rectifier filter circuits.
[0022] Figure 4 This is the second circuit schematic diagram of the switching devices and rectifier filter circuit.
[0023] Figure 5 This is one of the circuit schematics of the bidirectional equalizer controller based on isolated transmission according to the present invention.
[0024] Figure 6 This is one of the circuit schematics for the controllable load of the present invention.
[0025] Figure 7 This is the second circuit schematic of the bidirectional equalizer controller based on isolated transmission of the present invention. Detailed Implementation
[0026] The embodiments of this disclosure will now be described in detail with reference to the accompanying drawings.
[0027] The following specific examples illustrate the implementation of this disclosure. Those skilled in the art can easily understand other advantages and effects of this disclosure from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. This disclosure can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this disclosure. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.
[0028] This invention employs magnetic isolation technology from a transformer instead of optocoupler isolation, demonstrating significant advantages in high-voltage applications through transformer-based signal transmission. The transformer primarily relies on enameled wire, a mature technology readily available for voltages above 10kV, and widely produced domestically. However, the current error signal is a continuous analog signal, which transformers cannot transmit; therefore, adjustments to the circuit structure are necessary.
[0029] Signal transmission in optocouplers is unidirectional, as is the case with existing technologies. Figure 1 In reverse operation, optocoupler OPT1 is needed to transmit the enable signal from the primary side to the secondary side; in forward operation, optocoupler OPT2 is needed to transmit the current error signal from the secondary side to the primary side. The technical problem to be solved by this application is: how to put these two signals with opposite directions into an isolation device for transmission, and these two signals may need to be transmitted simultaneously.
[0030] The present invention provides a bidirectional equalizer controller based on isolated transmission, such as... Figure 2As shown, the system includes a second transformer T2, an oscillation circuit, switching devices, a forward PWM controller, a rectifier and filter circuit, a controllable load, a current error amplifier, and a reverse PWM controller. One end of the primary winding of the second transformer T2 receives the supply voltage VDD. The input of the oscillation circuit receives the reverse enable signal sent by the host computer, and its output is connected to the other end of the primary winding of the second transformer T2 via the switching devices. The two inputs of the forward PWM controller receive the forward enable signal and the voltage feedback signal VFB_P sent by the host computer, respectively. The input of the rectifier and filter circuit is connected to both ends of the secondary winding of the second transformer T2, and its output is connected to the input of the controllable load and the input of the reverse PWM controller. The current error amplifier samples the charging current of the battery being charged, amplifies the error, and outputs a voltage signal VEA to the control terminal of the controllable load. The controllable load draws a current signal IFB_S, monotonically correlated with the voltage signal VEA, from the output of the rectifier and filter circuit. This signal is then isolated and fed back to the primary winding via the secondary winding of the second transformer T2, forming a current feedback signal IFB_P, also monotonically correlated with the voltage signal VEA. The current feedback signal IFB_P is converted into a voltage feedback signal VFB_P, which is input to one input of the forward PWM controller. The forward PWM controller controls the charging current based on the voltage feedback signal VFB_P.
[0031] The core innovation of this application is a magnetically isolated transmission scheme composed of an oscillation circuit, switching devices, a second transformer T2, a rectifier and filter circuit, and a controllable load. This magnetically isolated transmission scheme can be understood as forming a low-power switching power supply. A switching power supply generally contains two signals: output voltage and output current. Signal transmission from left to right is relatively easy to understand; it's the normal function of a switching power supply output. When the primary side of the second transformer T2 has a supply voltage VDD and the oscillation circuit starts working, the secondary side of the second transformer T2, after passing through the rectifier and filter circuit, will output a voltage (denoted as the reverse enable voltage in the diagram). This is the process of signal transmission from left to right. Because the reverse enable voltage is used to enable or disable the reverse PWM control circuit, a threshold is generally set. When the reverse enable voltage is greater than this threshold, the reverse PWM controller is enabled or disabled; when the reverse enable voltage is less than this threshold, the opposite occurs. Therefore, the accuracy requirement for the voltage amplitude of the reverse enable voltage is not too high.
[0032] The current signal IFB_S is fed back from the secondary side to the primary side of the second transformer T2 in the following way: The controllable load draws the current signal IFB_S from the output of the rectifier filter circuit. The current signal IFB_S and the current IFB_P of the primary winding have a certain turns ratio relationship. The current IFB_P of the primary winding will change with the current signal IFB_S drawn from the secondary side. Therefore, by detecting the current IFB_P on the primary side, the current signal IFB_S drawn from the secondary side can be detected indirectly. Therefore, the current IFB_P of the primary winding is also called the current feedback signal.
[0033] In this application, the feedback signal is a continuous analog signal. The current error amplifier outputs a voltage signal VEA to the controllable load. The controllable load extracts a current signal IFB_S from the rectifier filter circuit based on the input voltage signal VEA. The current signal IFB_S and the voltage signal VEA are monotonically correlated. Monotonically correlated means that the current signal IFB_S follows the change of the voltage signal VEA; when the voltage signal VEA increases, the current also increases, and when the voltage signal VEA decreases, the current also decreases. This can be a linear or non-linear change. Since the primary and secondary currents of the second transformer are related by the turns ratio, the current signal IFB_P of the primary winding (i.e., the current feedback signal) and the voltage signal VEA output by the current error amplifier also exhibit a monotonically related relationship, thereby transferring the battery charging current from the secondary side to the primary side of the second transformer T2.
[0034] The switching devices and rectifier filter circuits in this application can be implemented using existing technologies, such as... Figure 3 and Figure 4 As shown. Theoretically, there are multiple combinations of topologies for the primary and secondary sides of the second transformer T2. For example, the primary side can use one of the following: flyback, forward, push-pull, half-bridge, full-bridge, etc. The oscillation circuit follows the type of these topologies, inputting a corresponding square wave to control the switching of MOSFET Q3. The secondary side can also use one of the following: half-wave rectification, full-wave rectification, bridge rectifier circuit, etc. The preferred solution is... Figure 3 The flyback circuit shown has the smallest components and the fewest transformer windings.
[0035] The following section explains the working principle of the monotonic correlation between the current feedback signal IFB_S and the voltage sampling signal, using a specific circuit structure as an example. Figure 5 As shown, the current error amplifier includes a first operational amplifier OP1 and a fourth capacitor C4. The non-inverting input of the first operational amplifier OP1 samples the charging current of battery 2 through a first resistor R1, the inverting input receives a reference voltage VREF, and the output outputs a voltage signal VEA. The fourth capacitor C4 is connected between the inverting input and the output of the first operational amplifier OP1. The fourth capacitor C4 can also be a resistor and a capacitor connected in series or in parallel, serving a compensation function.
[0036] The controllable load includes a first transistor Q4 and a third resistor R3. The collector of the first transistor Q4 serves as the input terminal of the controllable load, drawing a current signal IFB_S from the rectifier and filter circuit. The emitter of the first transistor Q4 is grounded. One end of the third resistor R3 serves as the control terminal of the controllable load, inputting the voltage signal VEA output from the first operational amplifier OP1, and the other end is connected to the base of the first transistor Q4.
[0037] The non-inverting input of the first operational amplifier OP1 samples the charging current I of battery C2 through the first resistor R1. 充 When the charging current I 充 When the voltage increases, the voltage at the non-inverting input of the first op-amp OP1 increases, the difference between the non-inverting and inverting inputs increases, and the voltage signal VEA output by the first op-amp OP1 also increases.
[0038] The current value of the current signal IFB_S drawn by the controllable load from the rectifier filter circuit is denoted as I. FB_S The calculation formula is as follows:
[0039] Formula (1).
[0040] Among them, V EA β is the output voltage of the current error amplifier, β is the current amplification ratio between the collector and base of transistor Q4, and R3 is the resistance value of the third resistor R3.
[0041] The current feedback signal IFB_P of the primary winding of transformer T2 is related to the current signal IFB_S of the secondary winding by the turns ratio, that is:
[0042] Formula (2).
[0043] Where, N P and N S These are the number of turns in the primary winding and the number of turns in the secondary winding of the second transformer T2, respectively.
[0044] As can be seen from formulas (1) and (2), the current feedback signal IFB_P is linearly correlated with the voltage signal VEA.
[0045] Furthermore, controllable loads can also be implemented using other circuit structures, such as... Figure 6As shown, the controllable load includes a fifth MOSFET Q5, a second operational amplifier OP2, a fifth capacitor C5, and a fourth resistor R4. The drain of the fifth MOSFET Q5 serves as the input terminal of the controllable load, drawing a current signal IFB_S from the rectifier and filter circuit. The source is grounded through the fourth resistor R4. The non-inverting input of the second operational amplifier OP2 serves as the control terminal of the controllable load, receiving the voltage signal VEA output from the first operational amplifier OP1. The inverting input of the second operational amplifier OP2 is connected to the drain of the fifth MOSFET Q5, and its output is connected to the gate of the fifth MOSFET Q5. The fifth capacitor C5 is connected between the inverting input and the output of the second operational amplifier OP2.
[0046] The fifth capacitor, C5, can be a resistor and a capacitor connected in series or in parallel, and mainly serves a compensation function.
[0047] Figure 6 The controllable load shown is equivalent to a constant current source. When the voltage signal VEA output by the first operational amplifier OP1 also increases, the voltage at the non-inverting input of the second operational amplifier OP2 increases, the voltage difference between the non-inverting and inverting inputs of the second operational amplifier decreases, the output voltage of the second operational amplifier OP2 decreases, the on-resistance of the fifth MOSFET Q5 increases, and ultimately the current signal IFB_S decreases, thus forming negative feedback. This negative feedback will control the input voltages at the non-inverting and inverting inputs of the second operational amplifier to tend to be equal. The current value of the current feedback signal IFB_P on the primary side of transformer T2 is:
[0048] Formula (3).
[0049] R4 is the resistance value of the third resistor R4.
[0050] From formula (3), it can be seen that the current feedback signal IFB_P is linearly related to the voltage signal VEA.
[0051] Combination Figure 5 This invention explains the working principle of the bidirectional equalizer controller based on isolated transmission:
[0052] During forward operation, the host computer sends a reverse enable signal to activate the oscillation circuit. The switching devices are in the switching state, and the primary winding of transformer T2 is energized. At this time, the reverse enable voltage output from the rectifier and filter circuit on the secondary winding of the second transformer T2 is a high-level signal. The reverse PWM controller receives a high-level signal and does not operate (this application defines the reverse PWM controller as not operating at a high level and operating at a low level), and the second MOSFET Q2 is in the off state. Simultaneously, the host computer sends a forward enable signal to control the forward PWM controller, which in turn controls the switching of the first MOSFET Q1, forming a flyback circuit with input from the left side and output from the right side of the first transformer T1, charging battery 2. The non-inverting input of the current error amplifier samples the forward charging current I through the first resistor R1.充 When the forward charging current I 充 When the voltage increases, the voltage at the non-inverting input of the first operational amplifier OP1 increases, the difference between the non-inverting and inverting inputs increases, and the output voltage VEA of the first operational amplifier OP1 also increases. From formulas (2) and (3), it can be seen that the current feedback signal IFB_P will increase along with the voltage signal VEA. The current feedback signal IFB_P, after passing through the second resistor R2, can be converted into a voltage feedback signal VFB_P. The formula for calculating the voltage value of the voltage feedback signal VFB_P is as follows:
[0053] Formula (4).
[0054] Among them, V FB_P For the feedback voltage value, V DD R1 is the supply voltage value of the primary side of the second transformer T2, and R2 is the resistance value of the second resistor R2.
[0055] When the feedback current value I FB_P When it increases, the feedback voltage value V FB_P It will become smaller. In this application, the positive PWM controller constitutes a voltage-type PWM control circuit, such as... Figure 5 As shown, it includes a sawtooth wave generator U3, a clock signal generator U1, an RS flip-flop U2, and a comparator U3. The smaller the voltage value of the feedback signal VFB_P, the smaller the duty cycle of the forward PWM control circuit output, the smaller the excitation current of the primary winding of transformer T1, and ultimately the smaller the forward charging current value I. 充 Decrease. Figure 5 The positive PWM controller forms a negative feedback circuit, where operational amplifier OP1 is the error amplifier for the entire negative feedback circuit. Based on the principle of virtual short at the op-amp input, the voltages at the two input ports of op-amp OP1 are equal, therefore, its output constant current value I is:
[0056] Formula (5).
[0057] The accuracy of the forward charging current is only related to the accuracy of the reference voltage and the accuracy of the current sampling resistor, i.e., the first resistor R1, and has high accuracy.
[0058] In reverse operation, the host computer controls the primary-side forward PWM controller to remain inactive, and the first MOSFET Q1 is turned off. Simultaneously, the control oscillation circuit is inactive, and the rectifier and filter circuit outputs a low level. When the reverse PWM control circuit receives a low-level signal, it begins operation, controlling the second MOSFET Q2 to turn on, thus forming a flyback circuit with input from the right side and output from the left side of the first transformer T1.
[0059] Furthermore, the forward PWM controller can also be a peak current PWM controller, with a circuit structure as follows: Figure 7 As shown, the sawtooth wave generator has been removed. The positive input of comparator U3 is connected to the source of the first MOSFET Q1 to sample the peak value of the magnetizing current. Besides this, any type of PWM controller can be used for the forward PWM controller, such as an average current PWM controller or a PFM controller. The reverse PWM controller can be one of the aforementioned forward PWM controllers.
[0060] This invention also provides a power converter, including the aforementioned bidirectional equalization controller based on isolated transmission, and further including a first transformer T1, a first MOSFET Q1, and a second MOSFET Q2. The drain of the first MOSFET Q1 is connected to one end of the primary winding of the first transformer T1, and the source of the first MOSFET Q1 is connected to the negative terminal of the power supply. The other end of the primary winding of the first transformer T1 is connected to the positive terminal of the power supply. The gate of the first MOSFET Q1 is connected to the output terminal of a positive PWM controller. The drain of the second MOSFET Q2 is connected to one end of the secondary winding of the first transformer T1, and the source of the second MOSFET Q2 is connected to the negative terminal of the battery. The other end of the secondary winding of the first transformer T1 is connected to the positive terminal of the battery. The gate of the second MOSFET Q2 is connected to the output terminal of a reverse PWM controller. A current error amplifier samples the secondary charging current.
[0061] When forward charging is required, the host computer sends a forward enable signal to the forward PWM controller and a reverse enable signal to the oscillation circuit. The forward signal conversion circuit operates, controlling the first MOSFET Q1 to conduct, charging battery 2 through the first transformer T1, forming a voltage transfer from the primary to the secondary side of the first transformer T1. The oscillation circuit controls the switching devices, and the rectifier and filter circuit outputs a high level, controlling the reverse PWM controller to turn off. The current error amplifier samples the charging current of battery C2 and outputs a voltage signal VEA to the controllable load. The controllable load extracts a current signal IFB_S from the rectifier and filter circuit based on the voltage signal, feeding it back to the forward PWM controller through the second transformer T2. This controls the duty cycle of the square wave signal output by the forward PWM controller, thereby controlling the excitation current of the primary winding of transformer T1 and the magnitude of the charging current to battery C2.
[0062] When reverse discharge is required, the host computer does not send forward or reverse enable signals. The forward PWM controller does not operate, and the first MOSFET Q1 is turned off. The oscillation circuit does not operate, the rectifier and filter circuit outputs a low level, the reverse PWM controller operates, the second MOSFET Q2 conducts, and battery C2 discharges, forming a voltage transfer from the secondary side to the primary side of the first transformer T1. The magnitude of the reverse discharge current is not limited in this invention.
[0063] The above description is merely illustrative of the embodiments of the present invention and is not intended to limit the present invention. For those skilled in the art, any modifications, equivalent substitutions, improvements, etc., made without creative effort within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A bidirectional equalizer controller based on isolated transmission, characterized in that, The system includes a second transformer T2, an oscillation circuit, switching devices, a forward PWM controller, a rectifier and filter circuit, a controllable load, a current error amplifier, and a reverse PWM controller. One end of the primary winding of the second transformer T2 receives the supply voltage VDD. The input of the oscillator circuit receives the reverse enable signal sent from the host computer, and its output is connected to the other end of the primary winding of the second transformer T2 via the switching devices. One input of the forward PWM controller receives the forward enable signal. The input of the rectifier and filter circuit is connected to both ends of the secondary winding of the second transformer T2, and its output is connected to the input of the controllable load and the reverse PWM controller. The input terminal of the controller; the current error amplifier samples the charging current of the battery, and after error amplification, outputs a voltage signal VEA to the control terminal of the controllable load; the controllable load extracts a current signal IFB_S that is monotonically related to the voltage signal VEA from the output terminal of the rectifier filter circuit, and then feeds it back to the primary winding through the secondary winding of the second transformer T2, forming a current feedback signal IFB_P that is monotonically related to the voltage signal VEA; the current feedback signal IFB_P is converted into a voltage feedback signal VFB_P and input to the other input terminal of the positive PWM controller; the positive PWM controller controls the charging current according to the voltage feedback signal VFB_P; The controllable load includes a first transistor Q4 and a third resistor R3; the collector of the first transistor Q4 serves as the input terminal of the controllable load and extracts the current signal IFB_S from the rectifier filter circuit, and the emitter of the first transistor Q4 is grounded; one end of the third resistor R3 serves as the control terminal of the controllable load and inputs the voltage signal VEA, and the other end is connected to the base of the first transistor Q4. The current error amplifier includes a first operational amplifier OP1 and a fourth capacitor C4; the non-inverting input of the first operational amplifier OP1 samples the charging current of the battery, the inverting input receives the reference voltage VREF, and the output outputs the voltage signal VEA; the fourth capacitor C4 is connected between the inverting input and the output of the first operational amplifier OP1. The monotonic correlation between the current feedback signal IFB_P and the voltage signal VEA is as follows: , where I FB_S N represents the current value of the current signal IFB_S. P and N S These represent the number of turns in the primary winding and the number of turns in the secondary winding of the second transformer T2, respectively. EA β is the output voltage of the current error amplifier, β is the current amplification ratio between the collector and base of transistor Q4, and R3 is the resistance value of the third resistor R3.
2. The bidirectional equalizer controller based on isolated transmission according to claim 1, characterized in that, The controllable load includes a fifth MOSFET Q5, a second operational amplifier OP2, a fifth capacitor C5, and a fourth resistor R4. The drain of the fifth MOSFET Q5 serves as the input terminal of the controllable load, drawing a current signal IFB_S from the rectifier filter circuit, and the source is grounded through the fourth resistor R4. The non-inverting input terminal of the second operational amplifier OP2 serves as the control terminal of the controllable load, inputting a voltage signal VEA. The inverting input terminal is connected to the drain of the fifth MOSFET Q5, and the output terminal is connected to the gate of the fifth MOSFET Q5. The fifth capacitor C5 is connected between the inverting input terminal and the output terminal of the second operational amplifier OP2.
3. The bidirectional equalizer controller based on isolated transmission according to claim 1, characterized in that, The switching device is one of the following: MOSFET, flyback circuit, forward circuit, half-bridge circuit, and full-bridge circuit.
4. The bidirectional equalizer controller based on isolated transmission according to claim 1, characterized in that, The rectifier and filter circuit is one of half-wave rectification, full-wave rectification, or bridge rectification.
5. The bidirectional equalizer controller based on isolated transmission according to claim 2, characterized in that, The fifth capacitor C5 can be replaced by a resistor and a capacitor connected in series, or a resistor and a capacitor connected in parallel.
6. The bidirectional equalizer controller based on isolated transmission according to claim 1, characterized in that, The fourth capacitor C4 can be replaced by a resistor and a capacitor connected in series, or a resistor and a capacitor connected in parallel.
7. The bidirectional equalizer controller based on isolated transmission according to claim 1, characterized in that, The forward PWM controller or reverse PWM controller is one of the following: voltage-type PWM controller, peak current-type PWM controller, average current-type PWM controller, and PFM controller.
8. A power converter, comprising a first transformer T1, a first MOSFET Q1, and a second MOSFET Q2, characterized in that, It also includes the bidirectional equalization controller based on isolated transmission as described in any one of claims 1 to 7; the drain of the first MOSFET Q1 is connected to one end of the primary winding of the first transformer T1, and the source of the first MOSFET Q1 is connected to the negative terminal of the power supply; the other end of the primary winding of the first transformer T1 is connected to the positive terminal of the power supply; the gate of the first MOSFET Q1 is connected to the output terminal of the positive PWM controller; the drain of the second MOSFET Q2 is connected to one end of the secondary winding of the first transformer T1, and the source of the second MOSFET Q2 is connected to the negative terminal of the battery; the other end of the secondary winding of the first transformer T1 is connected to the positive terminal of the battery; the gate of the second MOSFET Q2 is connected to the output terminal of the reverse PWM controller; and a current error amplifier samples the battery charging current.