CN104167921B - Switch power parallel maximum streaming digital control method and circuit - Google Patents

Abstract

The digital control method and circuit for parallel connection of switching power supplies with maximum current sharing provided by the embodiments of the present invention relate to the control of switching power supplies, have an output voltage self-recovery function, and can avoid vicious competition of output voltages among switching power supplies. The circuit includes: a maximum current sharing digital controller, which judges whether the current sharing difference signal is greater than the current sharing difference threshold; if the current sharing difference signal is greater than the current sharing difference threshold, when the current sharing control signal does not reach the maximum value, the Increase the current sharing control signal by one step; if the current sharing difference signal is less than the current sharing difference threshold, when the current sharing control signal does not reach the minimum value, reduce the current sharing control signal by one step; output the adjusted current sharing control signal. Mainly used for maximum current sharing digital control of switching power supply.

Description

Digital control method and circuit for maximum current sharing of switching power supplies in parallel

technical field

The invention relates to the control of switching power supplies, in particular to a digital control method and circuit for parallel connection of switching power supplies with maximum current sharing.

Background technique

Parallel connection of multiple switching power supplies to provide external load energy is an effective way to increase the output power of switching power supplies. However, to realize the parallel operation of multiple switching power supplies, a parallel operation control method is required.

The maximum current sharing method is a method to realize the parallel operation control of the switching power supply output, which is generally realized through a dedicated analog control chip and combined with some peripheral analog circuits. The output voltage control outer loop of the switching power supply adopts the voltage error amplifier inside UC3907, and the inner loop of current sharing control adopts the adjustment amplifier inside UC3907. achieve higher control accuracy.

When implementing the above method for maximum current sharing, the inventors found that: this method of using a dedicated analog control chip to achieve maximum current sharing control requires an additional control circuit, and changes in hardware are required when adjusting parameters. In addition, when performing current sharing control on multiple switching power supplies, the output voltage of each power supply will increase, and there is no control mechanism to reduce the output voltage back to the initial voltage. In severe cases, there will be vicious competition in the output voltage. Ultimately, the output voltage rises to an uncontrollable level.

Contents of the invention

In order to solve the above technical problems, the embodiment of the present invention provides a digital control method and circuit for maximum current sharing of switching power supplies in parallel, which can realize the maximum current sharing control of switching power supplies, and all have the function of output voltage self-recovery, which can avoid the The problem of vicious competition between output voltages.

The specific technical solutions are:

On the one hand, a digital control method for maximum current sharing of switching power supplies in parallel, including:

Query current sharing difference signal;

Judging whether the current sharing difference signal is greater than the current sharing difference threshold;

If the current sharing difference signal is greater than the current sharing difference threshold, it is judged whether the current sharing control signal reaches the maximum value;

If the current sharing control signal does not reach the maximum value, then increase the current sharing control signal by one step;

If the current sharing difference signal is less than the current sharing difference threshold, it is judged whether the current sharing control signal reaches the minimum value;

If the current sharing control signal does not reach the minimum value, then reduce the current sharing control signal by one step;

Outputting the adjusted current sharing control signal.

On the other hand, a switching power supply parallel maximum current sharing digital control circuit includes: a maximum current sharing digital controller, the maximum current sharing controller queries the current sharing difference signal; judges whether the current sharing difference signal is greater than the current sharing difference Threshold; if the current sharing difference signal is greater than the current sharing difference threshold, then judge whether the current sharing control signal reaches the maximum value; if the current sharing control signal does not reach the maximum value, then increase the current sharing control signal by one step; if the current sharing control signal If the difference signal is less than the current sharing difference threshold, it is judged whether the current sharing control signal reaches the minimum value; if the current sharing control signal does not reach the minimum value, the current sharing control signal is reduced by one step; the adjusted current sharing control signal is output Signal.

The switching power supply parallel connection maximum current digital control method and circuit provided by the embodiment of the present invention can increase the output voltage of the switching power supply whose output current signal is smaller than the current equalizing line signal, thereby increasing the output current value of the switching power supply to achieve the output The effect of increasing the output current of a switching power supply with a small current. After the switching power supply implements the maximum current sharing control, the output voltage of each output power supply reaches a balance point, so as to achieve the function of current sharing. In addition, among all parallel switching power supplies, the switching power supply with the largest output current will automatically reduce its own output voltage under the action of the maximum current sharing control method, thereby reducing the voltage between the output positive bus and the output negative bus. To achieve the function of automatic recovery of output voltage.

Description of drawings

The accompanying drawings are included to provide further understanding of the embodiments of the invention, and constitute a part of the specification, are used to illustrate the embodiments of the invention, and together with the description, explain the principle of the invention. Apparently, the drawings in the following description are only some embodiments of the present invention, and those skilled in the art can obtain other drawings according to these drawings without any creative effort.

Fig. 1 is a flow chart of a digital control method for parallel connection of switching power supplies with maximum current sharing provided by an embodiment of the present invention;

2 is a schematic structural diagram of a switching power supply parallel connection maximum current sharing digital control circuit provided by an embodiment of the present invention;

Fig. 3 is a schematic diagram of a maximum current sharing digital control circuit for multiple switching power supplies connected in parallel according to an embodiment of the present invention.

detailed description

Specific embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings. In the following description, for purposes of explanation and not limitation, specific details are set forth in order to provide a thorough understanding of the invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details.

It should be noted here that, in order to avoid obscuring the present invention due to unnecessary details, only the device structure and/or processing steps closely related to the solution according to the present invention are shown in the drawings, and the steps related to the present invention are omitted. Invent other details that don't really matter.

Example 1

An embodiment of the present invention provides a digital control method for maximum current sharing of switching power supplies connected in parallel, as shown in FIG. 1 , including:

101. Query current sharing difference signal;

102. Judging whether the current sharing difference signal is greater than the current sharing difference threshold;

103. If the current sharing difference signal is greater than the current sharing difference threshold, judge whether the current sharing control signal reaches the maximum value;

104. If the current sharing control signal does not reach the maximum value, increase the current sharing control signal by one step, and execute step 107;

105. If the current sharing difference signal is smaller than the current sharing difference threshold, judge whether the current sharing control signal reaches the minimum value;

106. If the current sharing control signal does not reach the minimum value, reduce the current sharing control signal by one step;

107. Outputting a current equalization control signal.

The switching power supply parallel connection maximum current digital control method provided in this embodiment makes the output voltage of the switching power supply whose output current signal is smaller than the current equalizing line signal increase, thereby increasing the output current value of the switching power supply, and achieving a smaller output current The effect of increasing the output current of the switching power supply. After the switching power supply implements the maximum current sharing control, the output voltage of each output power supply reaches a balance point, so as to achieve the function of current sharing. In addition, among all parallel switching power supplies, the switching power supply with the largest output current will automatically reduce its own output voltage under the action of the maximum current sharing control method, thereby reducing the voltage between the output positive bus and the output negative bus. To achieve the function of automatic recovery of output voltage.

Example 2

As an improvement of the above-mentioned embodiment, the embodiment of the present invention provides another digital control method for maximum current sharing of switching power supplies in parallel, which is realized by the circuit shown in Figure 2. The circuit includes a maximum current sharing digital controller, an adder, and a subtraction device, a current sampler, a diode, an output voltage reference generator, a switching power supply controller and a power supply main circuit.

Wherein, the output terminal of the output voltage reference value generator is connected to one of the positive input terminals of the adder, the output terminal of the maximum current sharing numerical controller is connected to the other positive input terminal of the adder, and the output terminal of the adder is connected to the switching power supply The input end of the controller is connected, the output end of the switching power supply controller is connected with the input end of the main circuit of the switching power supply, and the main circuit of the switching power supply has an output positive line and an output negative line. The current sampler is connected in series on the output positive line, one end of the output end of the current sampler is connected to the anode of the diode, the other end is connected to the negative end of the subtractor, and the cathode of the diode is connected to the current equalizing line. The current equalizing line signal on the current equalizing line enters the positive end of the subtractor, and the output end of the subtractor is connected to the input end of the maximum current equalizing digital controller.

The specific parallel maximum current sharing digital control method of the switching power supply includes:

First, the current sampler collects the output current signal on the positive output line. On the one hand, the output current signal enters the negative terminal of the subtractor, and on the other hand, enters the anode of the diode. The cathode of the diode is connected to the current sharing line, and the current sharing line The signal above is the current-sharing line signal, which enters the positive terminal of the subtractor. In the subtractor, the current-sharing line signal and the output current signal are subtracted to obtain the current-sharing difference signal, which enters the maximum current-sharing digital controller. .

Secondly, the maximum current sharing controller executes the control process shown in Figure 1 at a fixed frequency:

First query the current sharing difference signal, and then judge whether the current sharing difference signal is greater than the current sharing difference threshold, if the current sharing difference signal is greater than the current sharing difference threshold, then judge whether the current When the control signal reaches the maximum value, keep the current sharing control signal unchanged; if the current sharing control signal does not reach the maximum value, increase the current sharing control signal by one step. If when judging whether the current sharing difference signal is greater than the current sharing difference threshold, it is judged that the current sharing difference signal is smaller than the current sharing difference threshold, and then judge whether the current sharing control signal reaches the minimum value, if the current sharing control signal reaches the minimum value , keep the current sharing control signal unchanged, if the current sharing control signal does not reach the minimum value, then reduce the current sharing control signal by one step. Through the above control process, the maximum current sharing controller outputs a current sharing control signal.

The current sharing control signal generated by the maximum current sharing controller enters one positive terminal of the adder, and the output voltage reference value generator provides the output voltage reference signal to the other positive terminal of the adder, and the adder outputs the voltage reference signal and the equalizing After the flow control signal is added, a given voltage signal is obtained and provided to the switching power supply controller. The switching power supply controller generates a power supply control signal according to the given voltage signal and supplies it to the main circuit of the switching power supply to control the operation of the main circuit of the switching power supply.

When multiple switching power supplies output parallel operation, the connection mode of the circuit is shown in Figure 3. In the case of n switching power supplies, connect the output positive lines "+" of all switching power supplies to the output positive bus bar 303, and then connect all The output negative line "-" of the switching power supply is connected to the output negative bus bar 304 . Switching power supply 1 ( 301 ) to switching power supply n ( 302 ) supply power to load 309 through output positive bus 303 and output negative bus 304 . In addition, the current sharing lines of all switching power supplies are connected to the current sharing bus 305, and the maximum current sharing digital control method inside each switching power supply is used to ensure that each switching power supply outputs the same current.

When n switching power supplies are connected in parallel to supply power to the load 309, the signal on the current sharing bus 305 is the output current signal of the power supply with the largest output current from switching power supply 1 (301) to switching power supply n (305). 116, that is, the output current signal 116 of the power supply is the current sharing bus signal 306 on the current sharing bus. Since the current sharing line 119 of each switching power supply is connected to the current sharing bus 305 , all switching power supplies use the current sharing line signal 306 on the current sharing bus as their own current sharing line signal 117 .

The switching power supply parallel connection maximum current digital control method provided in this embodiment makes the output voltage of the switching power supply whose output current signal is smaller than the current equalizing line signal increase, thereby increasing the output current value of the switching power supply, and achieving a smaller output current The effect of increasing the output current of the switching power supply. After the switching power supply implements the maximum current sharing control, the output voltage of each output power supply reaches a balance point, so as to achieve the function of current sharing. In addition, among all parallel switching power supplies, the switching power supply with the largest output current will automatically reduce its own output voltage under the action of the maximum current sharing control method, thereby reducing the voltage between the output positive bus and the output negative bus. To achieve the function of automatic recovery of output voltage.

Example 3

An embodiment of the present invention provides a switching power supply parallel maximum current sharing digital control circuit, including: a maximum current sharing digital controller, the maximum current sharing controller queries the current sharing difference signal; judges whether the current sharing difference signal is greater than the current sharing difference value threshold; if the current sharing difference signal is greater than the current sharing difference threshold, then judge whether the current sharing control signal reaches the maximum value; if the current sharing control signal does not reach the maximum value, then increase the current sharing control signal by one step; If the current difference signal is less than the current sharing difference threshold, it is judged whether the current sharing control signal reaches the minimum value; if the current sharing control signal does not reach the minimum value, the current sharing control signal is reduced by one step; the adjusted current sharing control signal is output control signal.

In conjunction with Figure 2, the circuit also includes an adder, a subtractor, a current sampler, a diode, an output voltage reference value generator, a switching power supply controller, and a power supply main circuit group;

Among them, the current sampler collects the output current signal on the output positive line of the switching power supply. The output current signal enters the negative terminal of the subtractor on the one hand, and enters the anode of the diode on the other hand. The signal on the streamline is the current average signal, and the current average signal enters the positive terminal of the subtractor. In the subtractor, the current average signal and the output current signal are subtracted to obtain the current average difference signal, which enters the maximum current average digital controller;

The current sharing control signal generated by the maximum current sharing controller enters one positive terminal of the adder, and the output voltage reference value generator provides the output voltage reference signal to the other positive terminal of the adder, and the adder outputs the voltage reference signal and the equalizing After the flow control signal is added, a given voltage signal is obtained and provided to the switching power supply controller. The switching power supply controller generates a power supply control signal according to the given voltage signal and supplies it to the main circuit of the power supply to control the operation of the main circuit of the power supply.

The switching power supply provided by this embodiment is connected in parallel with the maximum current-sharing digital control circuit, so that the output voltage of the switching power supply whose output current signal is smaller than the signal of the current-sharing line increases, thereby increasing the output current value of the switching power supply, and achieving a smaller output current. The effect of increasing the output current of the switching power supply. After the switching power supply implements the maximum current sharing control, the output voltage of each output power supply reaches a balance point, so as to achieve the function of current sharing. In addition, among all parallel switching power supplies, the switching power supply with the largest output current will automatically reduce its own output voltage under the action of the maximum current sharing control method, thereby reducing the voltage between the output positive bus and the output negative bus. To achieve the function of automatic recovery of output voltage.

The maximum current-sharing digital control circuit with automatic voltage recovery function has simple structure, fast control, and less hardware resources. It not only has a good current-sharing effect, but also avoids the problem of vicious competition in output voltage. A core technology in flow control technology.

Features described and/or illustrated above for one embodiment may be used in the same or similar manner in one or more other embodiments, and/or be combined with or replace features in other embodiments Features in .

It should be emphasized that the term "comprising/comprising" when used herein refers to the presence of features, integers, steps or components, but does not exclude the presence or addition of one or more other features, integers, steps, components or combinations thereof .

The above circuits and methods of the present invention can be implemented by hardware, or by combining hardware and software. The present invention relates to such a computer-readable program that, when the program is executed by a logic unit, enables the logic unit to realize the above-mentioned circuits or constituent parts, or enables the logic unit to realize the above-mentioned various methods or steps. The present invention also relates to a storage medium for storing the above program, such as hard disk, magnetic disk, optical disk, DVD, flash memory and the like.

The many features and advantages of these embodiments are apparent from this detailed description, and thus the appended claims are intended to cover all such features and advantages of these embodiments that fall within their true spirit and scope. Moreover, since many modifications and changes will readily occur to those skilled in the art, it is not intended to limit the embodiments of the present invention to the precise structures and operations illustrated and described, but to cover all suitable modifications and equivalents falling within the scope thereof. thing.

Parts not described in detail in the present invention are well-known technologies for those skilled in the art.

Claims (5)

1. the maximum streaming digital control method of a kind of switch power parallel, it is characterised in that include：

Difference signal is flowed in inquiry；

Judge whether stream difference signal is more than and flow difference threshold；

If difference signal is flowed more than difference threshold is flowed, judge whether sharing control signal reaches maximum；

If sharing control signal is not reaching to maximum, sharing control signal is increased into a step-length；

If difference signal is flowed less than difference threshold is flowed, judge whether sharing control signal reaches minimum of a value；

If sharing control signal is not reaching to minimum of a value, sharing control signal is reduced into a step-length；

Sharing control signal after output adjustment.

2. method according to claim 1, it is characterised in that before the inquiry flows difference signal, also include；

On the one hand output current signal on the output main track of current sampler collection Switching Power Supply, the output current signal enter The negative terminal of subtracter, on the other hand into the anode of diode, the negative electrode of diode is connected on current equalizer, on the current equalizer Signal is current equalizer signal, and the current equalizer signal enters the anode of subtracter, by current equalizer signal and output current in subtracter Signal does subtraction, is flowed difference signal.

3. method according to claim 1 and 2, it is characterised in that also include：

Sharing control signal enters an anode of adder, and output voltage reference signal is carried by output voltage reference value generator Another anode of supply adder, in adder does output voltage reference signal and sharing control signal after addition, obtains Given voltage signal, and switch power controller is supplied to, switch power controller produces power supply control according to given voltage signal Signal processed is supplied to Switching Power Supply major loop, the work of controlling switch power supply major loop.

4. the maximum fluxion word control circuit of a kind of switch power parallel, it is characterised in that include：The control of maximum streaming digital Device, the maximum equalizing controller inquiry flow difference signal；Judge whether stream difference signal is more than and flow difference threshold；If Difference signal is flowed more than difference threshold is flowed, then judge whether sharing control signal reaches maximum；If sharing control signal Maximum is not reaching to, then sharing control signal is increased into a step-length；If flowing difference signal and being less than and flow difference threshold, Then judge whether sharing control signal reaches minimum of a value；If sharing control signal is not reaching to minimum of a value, sharing control is believed Number reduce a step-length；Sharing control signal after output adjustment.

5. circuit according to claim 4, it is characterised in that also including adder, subtracter, current sampler, two poles Pipe, output voltage reference value generator, switch power controller and power supply major loop group；

Wherein, the output current signal on current sampler collection Switching Power Supply output main track, the output current signal is on the one hand Into the negative terminal of subtracter, on the other hand into the anode of diode, the negative electrode of diode is connected on current equalizer, the current equalizer On signal be current equalizer signal, the current equalizer signal enter subtracter anode, by current equalizer signal and output in subtracter Current signal does subtraction, is flowed difference signal, into maximum streaming digital controller；

The sharing control signal that maximum equalizing controller is produced enters an anode of adder, and output voltage reference value occurs Output voltage reference signal is supplied to another anode of adder, adder that control is flowed by output voltage reference signal and by device After signal processed does addition, given voltage signal is obtained, and is supplied to switch power controller, switch power controller is according to given Voltage signal produces power control signal and is supplied to power supply major loop, controls the work of power supply major loop.