CN101931336B - Control method and control system of single-phase inverter - Google Patents

Abstract

The invention relates to a control method and a control system of a single-phase inverter. The control method comprises the following steps of: detecting the inverted inductive current to be used for inverted progressive limiting current by using two primary current transducers (CT); calculating the capacitance current by using a difference method, and indirectly calculating the load current according to a formula to be used for calculating load power; meanwhile, using the calculated capacitance current as the negative feedback of a current ring to realize two closed loop control of inverted voltage and capacitance current. Current detection can be completed by using a single current transducer, and the instantaneous value control and the load capacity calculation of the inverted voltage and the capacitance current under a single CT hardware circuit can be realized on software; thus, hardware cost is saved.

Description

The control method of single-phase inverter and control system

Technical field

The present invention relates to power technology, more particularly, relate to a kind of control method and control system of single-phase inverter.

Background technology

Traditional single-phase inversion adopts voltage, current double closed-loop control, and its algorithm need detect inversion inductive current and load current.The inversion inductive current is used for doing the feedforward that current inner loop negative feedback and hardware wave limiting, load current are used for calculating the inverter load capacity and do current inner loop, therefore need two current sensors on the hardware, as shown in Figure 1, the first current sensor CT1 is for detection of detecting inductive current, and the second current sensor CT2 is for detection of load current.

Fig. 2 is the block diagram of traditional single phase inverse control system.I among Fig. 2 _L(s) be inductive current, i _O(s) be load current, G _V(s) be Voltage loop controller, G _I(s) be current loop controller, the structure in the frame of broken lines is the equivalent structure block diagram of inverter.As shown in Figure 2, inductive current i _L(s), load current i _O(s) be fed back to current loop controller G _I(s) input, and at the signal synthesis point

Do+i _O(s) with-i _L(s) add operation.

Summary of the invention

The technical problem to be solved in the present invention is, at the defective that above-mentioned hardware quantity is many, cost is high of prior art, provides a kind of control method that adopts a current sensor to carry out the single-phase inverter of current detecting.

The present invention also provides a kind of control system that adopts a current sensor to carry out the single-phase inverter of current detecting.

The technical solution adopted for the present invention to solve the technical problems is: a kind of control method of single-phase inverter is provided, may further comprise the steps:

The current detecting step comprises: use current sensor with two former limits to inversion filter capacitor electric current and the load current sampling of described inverter, the secondary of described current sensor obtain described inversion filter capacitor electric current and load current vector and;

Inverter voltage detects step;

The capacitance current calculation procedure: comprise the inverter voltage of the described inverter of sampling and it is carried out difference, and according to formula $i_C\left(k\right)=\frac{C}{\mathrm{\ΔT}}\·\{u\left(k\right)-u(k-1)\}$ Calculate inversion filter capacitor current i _c(k), be used as the negative feedback of electric current loop; Wherein, in the described formula: C is that inversion filter capacitor capacity, u are that inverter voltage, u (k)-u (k-1) are poor with k-1 inverter voltage constantly constantly for k, and Δ T is the k moment and k-1 time difference constantly;

Inversion inductive current and load current calculate step: comprise according to described vector and and the capacitance current that draws of described capacitance current calculation procedure, calculate inversion inductive current and load current;

FEEDBACK CONTROL step: comprise the inversion filter capacitor current i that to calculate _c(k) feed back to the input of current loop controller, inverter voltage, capacitance current are carried out two closed-loop controls.

In the control method of single-phase inverter of the present invention, inversion inductive current and load current calculate step and comprise:

In the inversion mode of operation, described vector and for the inversion inductive current

According to formula $\stackrel{\→}{i_L}=\stackrel{\→}{i_C}+\stackrel{\→}{i_{\mathrm{LOAD}}}$ The capacitance current i that draws with the capacitance current calculation procedure _c(k), calculate load current;

In bypass operating mode, described filter capacitor electric current is zero, described vector and be load current.

In the control method of single-phase inverter of the present invention, described FEEDBACK CONTROL step also comprises: use described inversion inductive current that the inverse switch pipe is carried out wave limiting; Using described load current to carry out bearing power calculates.

The present invention solves another technical scheme that its technical problem adopts: the control system of constructing a kind of single-phase inverter, comprise current detection circuit, inverter voltage testing circuit and control circuit, described control circuit comprises Voltage loop controller and coupled current loop controller, wherein

Described current detection circuit comprises a current sensor with two former limits, and wherein the first former edge joint is in the filter capacitor loop of single-phase inverter, and the second former edge joint is between the moving contact and single-phase inverter output of the output relay of single-phase inverter; Described control circuit is connected with described inverter voltage testing circuit with the secondary of described current sensor;

Described control circuit also comprises computing unit, be used for obtaining induced current and the detected inverter voltage of inverter voltage testing circuit calculates the described single-phase inverter parameters needed of control according to described current sensor secondary, and use described induced current and the parameter that calculates is controlled described single-phase inverter.

In the control system of single-phase inverter of the present invention, it is the inversion inductive current that described current sensor secondary obtains induced current, and the described parameter that calculates comprises: inversion filter capacitor electric current and load current.

In the control system of single-phase inverter of the present invention,

Described inversion filter capacitor Current Negative Three-Point Capacitance is used for inverter voltage, capacitance current are carried out two closed-loop controls to the input of current loop controller;

Described inversion inductive current is used for the inverse switch pipe is carried out wave limiting;

Described load current is used for carrying out bearing power and calculates.

Implement the present invention, have following beneficial effect:

The present invention adopts single current sensor to finish current detecting, has realized that from software the control of inverter voltage, capacitance current instantaneous value and load capacity under the single current sensor hardware circuit calculate simultaneously.Thereby saved hardware cost, but still can satisfy following function:

1. inductive current detects, and is used for inverse switch pipe wave limiting;

2. the indirect calculation load current is used for load capacity and calculates;

3. the indirect calculation capacitance current is finished the two closed-loop controls of inversion.

Description of drawings

The invention will be further described below in conjunction with drawings and Examples, in the accompanying drawing:

Fig. 1 is the structural representation of traditional single phase inverter current testing circuit;

Fig. 2 is traditional single phase inverter control system block diagram;

Fig. 3 is the schematic diagram of single-phase inverter current detection circuit of the present invention;

Fig. 4 is the single-phase inverter inverse control system block diagram that the present invention adopts capacitor current feedback;

Fig. 5 is the flow chart of the control method of single-phase inverter of the present invention.

Embodiment

In order to save hardware cost, satisfy inversion output performance and logic simultaneously and judge the requirement of load, the present invention has conceived current detection scheme and the inversion control scheme of a current sensor of a kind of employing, and the present invention has changed current detection circuit dexterously and realized inverter voltage, the control of capacitance current instantaneous value and load capacity calculating under the single current sensor hardware circuit from software simultaneously.

Fig. 3 is the schematic diagram of single-phase inverter current detection circuit of the present invention.As shown in Figure 3, inductive current detects with load current and has detected a current sensor CT multiplexing, this current sensor CT has two former limits, a former edge joint is in inversion filter capacitor loop, another former edge joint after output relay, the electric current that this current sensor CT samples be load current and capacitance current vector and.

When inversion was worked, the electric current that current sensor CT records was capacitance current i _CWith load current i _LOADSum, capacitance current and load current sum are inversion inductive current i _L,

$\stackrel{\→}{i_L}=\stackrel{\→}{i_C}+\stackrel{\→}{i_{\mathrm{LOAD}}}---\left(1\right)$

Can draw from (1) formula: $\stackrel{\→}{i_{\mathrm{LOAD}}}=\stackrel{\→}{i_L}-\stackrel{\→}{i_C}---\left(1a\right)$ With $\stackrel{\→}{i_{\mathrm{LOAD}}}-\stackrel{\→}{i_L}=-\stackrel{\→}{i_C}---\left(1b\right).$

Can be seen that by Fig. 3 the inversion inductance L links to each other with Q2 with inverse switch pipe Q1, therefore the current signal that can record with current sensor CT (is inversion inductive current i _L) do inverse switch pipe wave limiting and use.

In addition, capacitance current $i_C=C\frac{\mathrm{du}}{\mathrm{dt}},$ Ask capacitance current so in algorithm of the present invention, can utilize the voltage difference:

$i_C\left(k\right)=\frac{C}{\mathrm{\ΔT}}\·\{u\left(k\right)-u(k-1)\}---\left(2\right)$

(2) C is inversion filter capacitor capacity in the formula, and u is inverter voltage; U (k)-u (k-1) is that k is poor with k-1 inverter voltage constantly constantly, and Δ T is the k moment and k-1 time difference constantly.Utilize (1), (2) formula to try to achieve load current i in the algorithm _LOADBe used for load calculation;

According to (1b) formula, the feedforward i of electric current loop among Fig. 2 _LOADFeedback-i with electric current loop _LSum is-i _CTherefore, the capacitance current that can try to achieve with the voltage difference branch is as the negative feedback of electric current loop;

Fig. 4 is the single-phase inverter control system block diagram that the present invention adopts capacitor current feedback, and wherein Cs is the transfer function of finding the solution capacitance current.

When bypass was worked, described filter capacitor electric current was zero, and according to (1a) formula, the detected electric current of current sensor CT is load current, was used for load calculation.The purpose of computational load: 1. show load capacity to the user, 2. do logic according to load capacity and judge (as: output is switched, transshipped and shut down after overload-alarm, duration of overload, the overload).

Fig. 5 is the flow chart of the control method of single-phase inverter of the present invention.As shown in Figure 5, in step 510, detect the inverter voltage of inverter.In step 512, use calculus of finite differences to calculate capacitance current based on inverter voltage based on detected inverter voltage in the step 510.In step 514, according to the capacitance current that calculates in the step 512, negative feedback is to the input of current loop controller, inverter voltage, capacitance current are carried out two closed-loop controls.

In step 520, current sensor detect inversion filter capacitor electric current and load current vector and, this vector and also be the inversion inductive current.In step 522, the capacitance current that calculates based on detected inversion inductive current and step 512 in the step 520 is according to formula $\stackrel{\→}{i_L}=\stackrel{\→}{i_C}+\stackrel{\→}{i_{\mathrm{LOAD}}}$ The computational load electric current.In step 524, use the inversion inductive current that the inverse switch pipe is carried out wave limiting; The working load electric current carries out bearing power and calculates, and is used for the load capacity demonstration and is with year logic to judge.

Need to prove that the present invention is not limited to the order of shown in Figure 5 or above-mentioned steps to the control method of single-phase inverter.For example, the use inversion inductive current in the step 524 carries out wave limiting to the inverse switch pipe and also can detect in step 520 after the inversion inductive current and carry out.

In another embodiment of the present invention, current detection scheme provided by the invention and inversion controlling method also can be used for not having the single-phase inverter of bypass output.Specific implementation method is that hardware detection inversion inductive current is used for doing the inversion wave limiting; Adopt calculus of finite differences to calculate capacitance current, according to formula (1) indirect calculation load current, be used for computational load power; Simultaneously with negative feedback realization inverter voltage, the capacitance current two closed-loop controls of the capacitance current that calculates as electric current loop.

Claims (6)

1. the control method of a single-phase inverter is characterized in that, may further comprise the steps:

The current detecting step comprises: use current sensor with two former limits to inversion filter capacitor electric current and the load current sampling of described inverter, the secondary of described current sensor obtain described inversion filter capacitor electric current and load current vector and;

Inverter voltage detects step;

The capacitance current calculation procedure: comprise the inverter voltage of the described inverter of sampling and it is carried out difference, and according to formula

Calculate inversion filter capacitor current i _c(k), be used as the negative feedback of electric current loop; Wherein, in the described formula: C is that inversion filter capacitor capacity, u are that inverter voltage, u (k)-u (k-1) are poor with k-1 inverter voltage constantly constantly for k, and Δ T is the k moment and k-1 time difference constantly;

Inversion inductive current and load current calculate step: comprise according to described vector and and the capacitance current that draws of described capacitance current calculation procedure, calculate inversion inductive current and load current;

FEEDBACK CONTROL step: comprise the inversion filter capacitor current i that to calculate _c(k) feed back to the input of current loop controller, inverter voltage, capacitance current are carried out two closed-loop controls.

2. according to the control method of the single-phase inverter of claim 1, it is characterized in that inversion inductive current and load current calculate step and comprise:

In the inversion mode of operation, described vector and for the inversion inductive current

According to formula

The capacitance current i that draws with the capacitance current calculation procedure _c(k), calculate load current;

In bypass operating mode, described filter capacitor electric current is zero, according to formula

Obtain

Described vector and be load current.

3. the control method of single-phase inverter according to claim 2 is characterized in that, described FEEDBACK CONTROL step also comprises: use described inversion inductive current that the inverse switch pipe is carried out wave limiting; Using described load current to carry out bearing power calculates.

4. the control system of a single-phase inverter comprises current detection circuit, inverter voltage testing circuit and control circuit, and described control circuit comprises Voltage loop controller and coupled current loop controller, it is characterized in that:

Described current detection circuit comprises a current sensor with two former limits, and wherein the first former edge joint is in the filter capacitor loop of single-phase inverter, and the second former edge joint is between the moving contact and single-phase inverter output of the output relay of single-phase inverter; Described control circuit is connected with described inverter voltage testing circuit with the secondary of described current sensor;

Described control circuit also comprises computing unit, be used for obtaining induced current and the detected inverter voltage of inverter voltage testing circuit calculates the described single-phase inverter parameters needed of control according to described current sensor secondary, and use described induced current and the parameter that calculates is controlled described single-phase inverter.

5. the control system of single-phase inverter according to claim 4 is characterized in that, it is the inversion inductive current that described current sensor secondary obtains induced current, and the described parameter that calculates comprises: inversion filter capacitor electric current and load current.

6. the control system of single-phase inverter according to claim 5 is characterized in that,

Described inversion filter capacitor Current Negative Three-Point Capacitance is used for inverter voltage, capacitance current are carried out two closed-loop controls to the input of current loop controller;

Described inversion inductive current is used for the inverse switch pipe is carried out wave limiting;

Described load current is used for carrying out bearing power and calculates.

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