WO2016192299A1

WO2016192299A1 - Method and circuit for equalizing current by controlling input current

Info

Publication number: WO2016192299A1
Application number: PCT/CN2015/093698
Authority: WO
Inventors: 梁新春; 李长远; 王吉信
Original assignee: 中兴通讯股份有限公司
Priority date: 2015-06-01
Filing date: 2015-11-03
Publication date: 2016-12-08
Also published as: CN106300985A

Abstract

A method and circuit for equalizing a current by controlling an input current. The method comprises: performing current sampling and power conversion on each of at least two inputs respectively to obtain a feedback input signal of each of the inputs (11); and outputting, according to the feedback input signal of each of the inputs, a compensation control signal to a compensation pin (COMP) of a PWM controller corresponding to each of the inputs (12).

Description

Current sharing method and circuit for controlling input current

Technical field

This application relates to, but is not limited to, the field of reverse power supply for switching power supplies.

Background technique

With the continuous development of communication network technology, while using the communication network for information flow, the communication network can also be used to propagate current to power the electrical equipment in the network. For example, using Ethernet to supply power to electronic devices such as network phones, wireless access points, surveillance cameras, and terminal switching devices in the network; for example, using telephone networks to telephones, long-lights, environmental monitoring devices, etc. in the telephone network. The device is powered. The communication network is used to supply power to the device, which solves the problem of difficulty in taking power, improves the flexibility of use of the device, reduces the installation complexity and the use cost of the device itself, and can remotely control the power supply or power-off of the device by using the communication network.

With the widespread use of communication network power supply technology, the power load in the communication network has a higher power demand. In order to supply power to a more powerful communication network, two or more power supply terminals are usually used to supply power to the same power load. When receiving the power supply from the power supply terminal, the interface control module first passes through the current sharing module to realize the same current in two or more power supply lines, and then passes through a DC/DC (Direct Current/Direct Current). Output to the power load. Due to the difference in the power supply distance of the power supply terminal and the loss in the power supply line, there is a problem of large voltage difference between each port of the interface control module. The related art scheme performs non-DC/DC conversion on each input port voltage (if similar Low-dropout linear regulator (LDO, low dropout regulator) linear voltage conversion, series resistors for voltage division) to compensate for the voltage difference between each input port to achieve current sharing, but the voltage compensation range of this method is limited, resulting in The current sharing effect is poor, and the greater the differential pressure at the input port, the greater the loss and the lower the efficiency.

In the related art solution, each power supply line also has a DC/DC voltage converter, and the current sharing is realized by adjusting the output voltage. 1 is a schematic structural view of a related art DC/DC converter. As shown in Figure 1, the DC/DC converter includes an input section (Input), a current sense circuit (Current sense), a power conversion circuit (DC/DC), a feedback circuit (Feedback), and a pulse width modulation controller (Pulse Width Modulation). Control, PWM control). among them, The input section may include an anti-surge circuit, an anti-reverse circuit, a filter circuit, a slow start circuit, and the like. The current sampling circuit is used to sample the input current cycle by cycle (for example, for a current mode control converter) or sample current for overcurrent protection (for example, for a non-current type control converter). In addition, the way to sample current is usually a resistor or current transformer. The power conversion circuit can include a power switch tube, a power diode, a power inductor, and a power transformer for the isolation circuit. The feedback circuit can include a voltage divider resistor, an operational amplifier, and an optocoupler can be used for the isolation circuit. The feedback circuit processes the output voltage or current information and transmits it to the PWM control chip. The PWM control chip forms the required duty cycle to control the power switching device through the collected information.

In addition, FIG. 2 is a schematic structural diagram of a current sharing method of the related art. The content shown in FIG. 2 is a parallel connection of a plurality of structures of FIG. 1, and the number of parallel connections may be any natural number of 1 or more. Among them, each circuit needs to add a current processing process (Share process), this part is operated to form a sharing bus (Share Bus) voltage, and according to its own current and the voltage of the current sharing bus, form a signal to control the output voltage, Achieve the current sharing effect.

However, the dynamic characteristics of the current sharing in the above manner cannot be guaranteed, and as the power supply line increases, the number of DC/DC voltage converters increases, and the accuracy of the current sharing will decrease.

Summary of the invention

The following is an overview of the topics detailed in this document. This Summary is not intended to limit the scope of the claims.

This paper provides a current sharing method and circuit for controlling input current, which is used to solve the problem that the related art cannot guarantee the current sharing dynamic characteristics and the high current sharing accuracy.

A current sharing method for controlling input current includes: respectively performing current sampling and power conversion on each of at least two inputs to obtain a feedback input signal of each channel; and outputting a compensation control signal according to a feedback input signal of each channel A compensation pin COMP of the corresponding pulse width modulation PWM controller is input to each of the paths.

Optionally, the PWM controller is a current mode PWM controller with independent COMP or equivalent COMP.

Optionally, the current sampling and power are respectively performed on each of the at least two inputs Converting, obtaining the feedback input signal of each channel includes: respectively sampling each of the at least two inputs into a cycle-by-cycle sampling peak current or average current to obtain a sampling current output signal of each channel; respectively, sampling current output signals for each channel After the power conversion, the feedback input signal of each channel is obtained.

Optionally, the current sampling and power conversion are respectively performed on each of the at least two inputs, and after obtaining the feedback input signal of each channel, the method further includes: sampling the current output signal obtained by outputting each input for current sampling. Input the current sampling input pin of the corresponding PWM controller for each channel.

Optionally, the outputting the compensation control signal to the COMP of the PWM controller corresponding to each input according to the feedback input signal of each channel comprises: sampling the feedback input signal of each channel to obtain a sampling signal, The sampling signal is subjected to proportional, supplemental or isolation processing to obtain a compensation control signal; and the compensation control signal is output to the COMP of the corresponding PWM controller for each of the inputs.

A current sharing circuit for controlling an input current, comprising: a feedback circuit, at least two current sampling circuits, at least two power conversion circuits, and at least two PWM controllers, the current sampling circuit, the power conversion circuit, and PWM The number of controllers is consistent with the number of input channels. Each input connection is connected to a current sampling circuit and a power conversion circuit. Each current sampling circuit is respectively connected to a corresponding one of the power conversion circuit and one PWM controller, and all power conversions are performed. The output of the circuit is connected to the feedback circuit, the output of which is connected to the COMP of all PWM controllers.

Optionally, the current sampling circuit is configured to: sample the peak current or the average current corresponding to each input cycle by cycle.

Optionally, the current sampling circuit is configured to: output a sampling current output signal obtained by current sampling corresponding to each input to a current sampling input pin of the corresponding PWM controller.

Optionally, the feedback circuit is configured to: sample the feedback input signal of each channel to obtain a sampling signal, and perform proportional compensation, supplementation, or isolation processing on the sampling signal to obtain compensation control Signal.

A computer readable storage medium storing computer executable instructions for performing the method of any of the above.

In the embodiment of the present invention, current sampling and power conversion are respectively performed on each of the at least two inputs to obtain a feedback input signal of each channel; and according to the feedback input signal of each channel, the output compensation control signal is output to each input corresponding to each channel. The PWM controller compensates for the pin COMP. In this way, there is no need to use the current sharing bus, and the current sharing current is not required by the related art to adjust the output voltage, and the input current of each cycle is directly adjusted, thereby reducing the current sharing, thereby ensuring dynamic characteristics and high current sharing accuracy. Moreover, the current sharing accuracy does not decrease due to an increase in the number of input parallel paths. At the same time, the number of devices used is reduced and the cost is reduced.

Other aspects will be apparent upon reading and understanding the drawings and detailed description.

BRIEF abstract

1 is a schematic structural view of a related art DC/DC converter;

2 is a schematic diagram of a current sharing method of the related art;

3 is a flowchart of a method for controlling a current sharing current of an embodiment according to an embodiment of the present invention;

4 is a schematic diagram of a current sharing circuit for controlling an input current according to an embodiment of the present invention;

FIG. 5 is a schematic diagram of a current sharing circuit for controlling an input current according to an application example of the present invention; FIG.

Figure 6 is a schematic diagram of a current mode control chip applied to an embodiment of the present invention.

Embodiments of the invention

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

As shown in FIG. 3, an embodiment of the present invention provides a current sharing method for controlling an input current, including the following steps:

Step 11: Perform current sampling and power conversion on each of the at least two inputs to obtain a feedback input signal for each channel.

Step 12: According to the feedback input signal of each channel, output a compensation control signal to each of the corresponding PWM controller compensation pins COMP.

Among them, the PWM controller is a current-mode PWM controller with independent COMP or equivalent COMP.

In this case, current sampling and power conversion are respectively performed on each of the at least two inputs, and the feedback input signal of each channel is obtained: sampling the peak current or the average current by cycle-by-cycle for each of the at least two inputs respectively. The sampling current output signal of each channel is obtained; after each of the sampling current output signals of each channel is subjected to power conversion, a feedback input signal of each channel is obtained.

In this case, current sampling and power conversion are respectively performed on each of the at least two inputs, and after obtaining the feedback input signal of each channel, the method further includes: outputting the sampling current output signal obtained by sampling each current input current to Each input is input to the current sampling input pin of the corresponding PWM controller.

In this case, according to the feedback input signal of each channel, outputting the compensation control signal to the COMP of the PWM controller corresponding to each input includes: sampling the feedback input signal of each channel to obtain a sampling signal, and sampling the signal A compensation control signal is obtained after performing proportional, supplemental or isolation processing; and the compensation control signal is output to the COMP of the corresponding PWM controller for each of the inputs.

FIG. 4 is a schematic diagram of a current sharing circuit for controlling an input current according to an embodiment of the present invention. As shown in FIG. 4, the current sharing circuit for controlling input current according to an embodiment of the present invention includes a feedback circuit 41 (Feedback) and at least two current sampling circuits (a first current sampling circuit 421, a second current sampling circuit 422, and a second N circuit sampling circuit 423), at least two power conversion circuits (first power conversion circuit 431, second power conversion circuit 432, Nth power conversion circuit 433) and at least two PWM controllers (first PWM controller 441, The second PWM controller 442 and the Nth PWM controller 443). The number of the current sampling circuit, the power conversion circuit, and the PWM controller is consistent with the number of inputs (the first input portion 451, the second input portion 452, and the Nth input portion 453), and each input is connected to a corresponding current. The sampling circuit and a power conversion circuit, and each current sampling circuit is respectively connected to a corresponding one of the power conversion circuit and one PWM controller. The output of all power conversion circuits is connected to a feedback circuit 41 whose output is connected to the COMP of all PWM controllers.

As shown in FIG. 4, the first input portion 451 is connected to the first current sampling circuit 421 and the first power conversion circuit 431. The first current sampling circuit 421 is connected to the first power conversion circuit 431 and the first PWM controller 441; The portion 452 is connected to the second current sampling circuit 422 and the second power conversion circuit 432. The second current sampling circuit 422 is connected to the second power conversion circuit 432 and the second PWM controller 442. The Nth input portion 453 is connected to the Nth circuit sampling circuit 423. And the Nth power conversion circuit 433, the Nth circuit sampling circuit 423 is connected to the Nth power conversion circuit 433 and the Nth PWM controller 443. The output of the power conversion circuit (including the first power conversion circuit 431, the second power conversion circuit 432, the Nth power conversion circuit) is connected to the feedback circuit 41, and the output of the feedback circuit 41 is connected to the PWM controller (including the first PWM controller) 441, COMP of the second PWM controller 442 and the Nth PWM controller 443).

As shown in Figure 4, each input has an independent PWM controller, separate current sampling circuitry, and independent power conversion circuitry. The input of each input through the current sampling circuit and the power conversion circuit is connected in parallel and provided to the feedback circuit 41. The output of the feedback circuit 41 is simultaneously sent to the COMP of each PWM controller.

The PWM controller is a current-mode PWM controller with independent COMP (for example, current-mode PWM control chip UC3842), or a current-mode PWM controller with equivalent COMP. The power conversion circuit includes a power tube, a capacitor, and an inductor, or may also include a transformer, a diode, or the like.

The feedback circuit 41 is configured to: sample the feedback input signal of each channel to obtain a sampling signal, and perform a proportional, complementary or isolated processing on the sampling signal to obtain a compensation control signal. The output of the feedback circuit 41 (compensation control signal) is simultaneously sent to the COMP of each PWM controller, and the compensation control signal can be directly sent; or the processed signal, such as an operational amplifier followed by an improved drive. Ability, or scale up or down, etc.

The current sampling circuit is configured to: output a sampling current output signal obtained by current sampling corresponding to each input to a current sampling input pin (Current Sense Input pin) of the corresponding PWM controller. The current sampling method may be resistance sampling or current transformer sampling. In addition, the peak current may be sampled cycle by cycle, or the average current may be sampled to improve the current sharing accuracy, or other processing methods may be adopted.

FIG. 5 is a schematic diagram of a current sharing circuit for controlling an input current according to an embodiment of the present invention. As shown As shown in Figure 5, this embodiment employs two independent inputs. Among them, the main power topology uses an isolated flyback converter circuit. The PWM controller is the UC3842 controller, the current sampling is obtained by resistor sampling, and the feedback circuit is realized by the parallel voltage regulator integrated circuit TL431 and the isolated optocoupler.

In this embodiment, two independent inputs share a feedback signal and are sent to the COMP of each PWM controller.

Figure 6 is a schematic diagram of a current mode control chip applied to an embodiment of the present invention. Here, the PWM controller employs, for example, a current type control chip as shown in FIG. 6.

Wherein, the current-type control chip compares the sampled current value with a certain reference value according to the sampled current (as obtained by the lead 3 (5)), and when the reference value is greater than the current sample value, The duty cycle is effectively turned on; when the current sampling value is greater than the reference value, the comparator operates, the duty cycle is turned off, and then the cycle ends, ready for the next switching cycle. Among them, the reference value compared with the current sample value is processed by the signal of COMP (ie, pin pin1(1)). In the UC3842, the COMP pin voltage passes through two diodes first, and then is divided by a resistor of 2R to 1R. In other words, the output voltage is controlled by COMP, and the input current is controlled by the Current Sense Input pin (pin3(5)). When all parallel circuits share a COMP, each parallel circuit regulates its own output voltage to the same value. In addition, each current uses its own input to the Current Sense Input pin, so each cycle regulates its own current. Since the voltage reference is a common one, even if the input voltage of each channel is different, the adjusted current value is the same. In order to improve the accuracy of the regulation current, the sampling current can be processed by the average value and then sent to the Current Sense Input pin. In this regard, by using a capacitor, the average value of the current can be easily obtained. Each conversion circuit can be set to the same switching frequency. Thus, the input current is the same for each switching cycle, and the input current is the same for the entire period. The input current for the entire period is equal to the input current per switching period multiplied by the switching frequency.

In summary, the embodiment of the present invention realizes the current sharing with better dynamic characteristics by controlling the input current cycle by cycle, and there is no problem that the current ring is oscillated due to the current loop adjustment. In addition, since there is no current sharing bus and a feedback circuit is shared, this current sharing method saves a lot of devices and achieves the advantages of saving volume and reducing cost. Moreover, since there is no current sharing bus, the current sharing accuracy of this current sharing method does not reduce the current sharing accuracy due to an increase in the number of paths.

One of ordinary skill in the art will appreciate that all or a portion of the steps of the above-described embodiments can be implemented using a computer program flow, which can be stored in a computer readable storage medium, such as on a corresponding hardware platform (eg, The system, device, device, device, etc. are executed, and when executed, include one or a combination of the steps of the method embodiments.

Alternatively, all or part of the steps of the above embodiments may also be implemented by using an integrated circuit. These steps may be separately fabricated into individual integrated circuit modules, or multiple modules or steps may be fabricated into a single integrated circuit module. achieve.

The devices/function modules/functional units in the above embodiments may be implemented by a general-purpose computing device, which may be centralized on a single computing device or distributed over a network of multiple computing devices.

When the device/function module/functional unit in the above embodiment is implemented in the form of a software function module and sold or used as a stand-alone product, it can be stored in a computer readable storage medium. The above mentioned computer readable storage medium may be a read only memory, a magnetic disk or an optical disk or the like.

Industrial applicability

The embodiment of the invention does not need to use the current sharing bus, and does not need to adjust the output voltage to achieve current sharing, directly adjust the input current of each cycle, and reduce the current sharing link, thereby ensuring dynamic characteristics and high current sharing precision. Moreover, the current sharing accuracy does not decrease due to an increase in the number of input parallel paths. At the same time, the number of devices used is reduced and the cost is reduced.

Claims

A current sharing method for controlling input current, comprising:

Current sampling and power conversion are respectively performed on each of the at least two inputs to obtain a feedback input signal of each channel;

According to the feedback input signal of each channel, the compensation control signal is output to the compensation pin COMP of the corresponding pulse width modulation PWM controller for each of the inputs.
The method of claim 1 wherein said PWM controller is a current mode PWM controller having a separate COMP or equivalent COMP.
The method of claim 1 , wherein the current sampling and power conversion are performed on each of the at least two inputs, respectively, and the feedback input signals of each channel are:

Sampling the peak current or the average current cycle by cycle for each of the at least two inputs, respectively, to obtain a sampled current output signal of each channel;

After each of the sampling current output signals of each channel is power-converted, a feedback input signal of each channel is obtained.
The method of claim 1 , wherein the current sampling and power conversion are respectively performed on each of the at least two inputs, and after obtaining the feedback input signal of each channel, the method further comprises: outputting each input for current sampling. The obtained sampled current output signal is input to the current sampling input pin of the corresponding PWM controller for each input.
The method of claim 1, wherein the outputting the compensation control signal to the COMP of the corresponding PWM controller according to each of the feedback input signals comprises: performing feedback input signals for each of the paths Sampling to obtain a sampling signal, and performing proportional, complementary or isolation processing on the sampling signal to obtain a compensation control signal; and outputting the compensation control signal to each of the COMPs corresponding to the PWM controller.
A current sharing circuit for controlling input current, comprising:

a feedback circuit, at least two current sampling circuits, at least two power conversion circuits, and at least two PWM controllers, the number of the current sampling circuit, the power conversion circuit, and the PWM controller are consistent with the number of input channels, Each current input circuit corresponds to a current sampling circuit and a power conversion circuit, and each current sampling circuit is respectively connected with a corresponding one of the power conversion circuits And a PWM controller, the outputs of all of the power conversion circuits are connected to the feedback circuit, the output of which is connected to the COMP of all PWM controllers.
The circuit of claim 6 wherein: said PWM controller is a current mode PWM controller having a separate COMP or equivalent COMP.
The circuit of claim 6 wherein: said current sampling circuit is configured to sample the peak current or average current corresponding to each input on a cycle-by-cycle basis.
The circuit of claim 6 wherein said current sampling circuit is configured to: output a sampled current output signal obtained by current sampling corresponding to each input to a current sampling input pin of a corresponding PWM controller.
The circuit of claim 6 wherein: said feedback circuit is configured to: sample a feedback input signal of each of said paths to obtain a sampled signal, and perform proportional, complementary or isolated processing on said sampled signal to obtain compensation control signal.
A computer readable storage medium storing computer executable instructions for performing the method of any of claims 1-5.