CN100413200C - Inverse Control Current Tracking Control Method Based on Average Current Compensation - Google Patents

Abstract

A reverse control current tracking control method based on average current compensation, which belongs to the technical field of current tracking control. The specific steps are as follows: 1) The measurement signal is output through a resettable integrator; 2) The average current model of the device is established; 3) The feedback amount is calculated (kT); 4) From the recursive relationship of the instantaneous current of the device, that is, the relationship of i _c (kT) recursively deduced from i _c (kT+T), the control law is reversed, and the output of the controller is obtained—the guide of the full-control switch 5) The constant frequency triangular wave is compared with the duty cycle corresponding to the output of the controller to obtain the PWM pulse that drives and controls the full control switch to be turned on and off. The present invention eliminates the influence of resonance or peak signal caused by switching element commutation on the control, does not need another input filter, and reduces the influence of two sudden changes in the measurement signal. Fast tracking and no distortion.

Description

Inverse Control Current Tracking Control Method Based on Average Current Compensation

technical field

The invention relates to a current tracking control method, in particular, an inverse control current tracking control method based on average current compensation. The invention belongs to the technical field of current tracking control.

Background technique

For the problem of current tracking control, the commonly used methods at home and abroad are: linear current control (Linear Current Control) method, hysteresis current control (Hysteresis current control) method. Among them, the linear current control method has a large error in tracking high-order harmonics; the modulation frequency of the hysteresis current control method is not fixed, and the switching frequency of the power conversion device is high, which is not only difficult to design the input filter, but also easily causes grid oscillation. It is also not conducive to fast transient control.

After searching the existing technical literature, it was found that K.Nishida, M.Rukonuzzman and M.Nakaoka in "Advanced Current Control Method Using Robust Deadbeat Algorithm for Single-phase Shunt Voltage Source Active Filter" ( Power application, (British) Journal of the Institute of Electrical Engineers, 151(3), 2004, pp.283-288) mentioned the digital dead-beat control (Digital Dead-beat Control) method, which starts from the continuous model, and then Discretization, and then deduce the control law, and output the pulse signal to control the full control switch through PWM. Its disadvantages: Since the continuous model cannot reflect the actual working conditions, the control law derived after discretization cannot achieve precise control; directly sample and control the instantaneous current, which will cause the resonance or spike signal caused by the commutation of the switching element brought into the control, causing system instability; without any compensation for the measurement signal, the impact on the control is greater when the reference signal changes suddenly; the input filter is required to filter out high-order harmonics, but it is not considered in the modeling, which will cause The system is unstable; it has inherent calculation delay, which will affect the dynamic response speed and compensation accuracy, and the tracking error of the sudden change signal is relatively large.

Contents of the invention

The purpose of the present invention is to overcome the disadvantages of the prior art, and provide an inverse control current tracking control method based on average current compensation, which has fast dynamic response speed and high compensation accuracy.

The present invention is realized through the following technical scheme. The present invention adopts the output of the measurement signal through the resettable integrator, establishes the average current model of the device, calculates the feedback amount, and then deduces the inverse control law to obtain the conduction time of the full-control switch, and finally passes the PWM output. Concrete steps of the present invention are as follows:

1. The measurement signal is output through a resettable integrator, which eliminates the influence of resonance or peak signals on the control caused by the commutation of switching elements.

This resettable integrator is reset every PWM switching period, and its output is the average value of the measured signal within one PWM period.

2. Establish the average current model of the device, calculate the difference between the two times before and after the average current model as compensation, and reduce the impact of the two sudden changes before and after the measurement signal.

When the full control switch of the power electronic device is turned on and off, according to the current flowing through the device connected to the grid reactor, the transient relationship between the output current of the device, the power supply voltage and the DC side capacitor voltage is listed.

When one pair of diagonal full-control switches is turned on and the other is turned off, the relationship between the output current of the device, the power supply voltage and the DC side capacitor voltage is:

${\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; kT</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; td</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; dc</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; L</span>}}\mathrm{<span\; class="notranslate">\; td</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; kT</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

Among them, i _c is the output current of the device, u _dc is the DC side capacitor voltage, u _s is the AC power supply voltage, L is the reactance value of the device connected to the grid, T is the PWM switching period of the device, td is the pair of full control switches On-time during one PWM switching cycle.

When the other pair of diagonal full-control switches is turned on and the others are turned off, the relationship between the output current of the device, the power supply voltage and the DC side capacitor voltage is:

${\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; kT</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; td</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; dc</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; td</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; kT</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; td</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

Substituting formula (1) into formula (2), the instantaneous current relationship of the device can be obtained as:

${\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; kT</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; dc</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; kT</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; td</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; kT</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; ]</span>\frac{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; kT</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; L</span>}}\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; kT</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

The average current model of the device can be obtained by integrating formula (1) and formula (2) in one PWM switching period:

$\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; kT</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; kT</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; dc</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; kT</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; td</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; kT</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; dc</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; kT</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; kT</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>\mathrm{<span\; class="notranslate">\; T</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

where _ic is the average current of the device during one PWM switching cycle.

由测量信号经可复位积分器的输出和平均电流模型前后两次的差值相加获得。这样不仅消除了由于开关元件换流引起的谐振或尖峰信号对控制的影响，而且减少测量信号前后两次突变带来的影响。3. Calculate the amount of feedback Feedback amount

It is obtained by adding the output of the measurement signal through the resettable integrator and the difference between the two times before and after the average current model. This not only eliminates the influence of resonance or peak signal on the control caused by the commutation of switching elements, but also reduces the influence of two sudden changes before and after the measurement signal.

4. The control law is deduced in reverse from the instantaneous current relationship of the device, and the conduction time of the full control switch is obtained.

代替，并逆推全控开关导通时间td，可得控制规律为：In order to track the reference signal i _ref (kT+T) (the reference signal i _ref (kT+T) is any signal to be tracked in the present invention), the i _c (kT+T) in the formula (3) is used by the reference signal i _ref (kT+T) instead, i _c (kT) uses the feedback amount of the present invention

Substitute, and inversely deduce the conduction time td of the full-control switch, the control law can be obtained as:

$\mathrm{<span\; class="notranslate">\; td</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; kT</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span><span\; class="notranslate">\; \{</span><span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; ref</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; kT</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\stackrel{<span\; class="notranslate">\; ^</span>}{\mathrm{<span\; class="notranslate">\; i</span>}}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; kT</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>\frac{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; kT</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; dc</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; kT</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \}</span>\frac{\mathrm{<span\; class="notranslate">\; T</span>}}{{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; dc</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; kT</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; )</span>$

5. Use a constant frequency triangular wave as the carrier wave for PWM tracking, and compare it with the duty ratio corresponding to the output of the controller to obtain the PWM pulse that drives and controls the full control switch to be turned on and off. When the modulation frequency is not fixed, it is not only difficult to design the input filter, but also easy to cause grid oscillation, and it is also not conducive to fast transient control.

The output of the controller is multiplied by the switching frequency to obtain the duty ratio corresponding to the output of the controller. The duty ratio is compared with the constant frequency triangle wave to obtain the PWM pulse to drive and control the on and off of the full control switch, so that The output waveform of the control power electronics device tracks the reference signal quickly and accurately.

Since the switching frequency of the power electronic device is relatively high, generally reaching 10kHz and above, it can be considered that the power supply voltage and the DC side capacitor voltage remain unchanged during a PWM switching cycle. The invention adopts the measurement signal to output through the resettable integrator, and eliminates the influence of the resonance or peak signal caused by the commutation of the switch element on the control. The feedback quantity is composed of the sum of two parts: one part is the output of the measurement signal through the resettable integrator, and the resettable integrator is reset once every PWM switching cycle, so the output of the resettable integrator is the output of the measurement signal in a PWM The average value in the switching period; the other part is the difference between the two times before and after the output of the average current model. Using such a feedback amount can not only eliminate the resonance or peak signal caused by the commutation of the switching element, but also reduce the impact of the two sudden changes before and after the measurement signal. The triangular wave tracking PWM mode of the present invention has the best effect.

Beneficial effects of the present invention: a discrete model is directly established according to the working state of each full-control switch to reflect the actual working situation, and the control rule derived from this can accurately track the reference signal of any waveform; the resettable integrator filtering scheme is adopted, which can eliminate The influence of resonance or peak signal caused by switching element commutation on the control; the resettable integrator filtering scheme is adopted, and no additional input filter is required; the difference between the two times before and after the average current model is used to output the resettable integrator Compensating the output of the reference signal can reduce the impact of the two sudden changes of the measurement signal; due to the compensation, the reference signal can also be quickly tracked without distortion when the reference signal changes suddenly.

Description of drawings

Schematic diagram of the inverter unit structure of the device in Figure 1

Figure 2 Triangular wave carrier PWM diagram

Fig. 3 principle schematic diagram of the present invention

The current tracking waveform diagram in the embodiment of the present invention in Fig. 4

Figure 5 is a diagram of the power output current variation caused by the load variation in the embodiment of the present invention

Detailed ways

Provide following embodiment in conjunction with content of the present invention:

为本发明采用的反馈量；逆变器是图1所示的电力电子装置，i_c是装置的输出电流，u_dc是装置直流侧电容电压，u_s是装置交流电源电压；复位积分是可复位积分器，它每PWM开关周期复位一次，这样，可复位积分器的输出就是i_c在一个PWM开关周期内的平均值；平均电流模型是式(4)所表示的装置的平均电流模型；Z-1表示信号比当前时刻延时一个PWM开关周期，这样可以得到平均电流模型前后两次的输出，它们的差值去补偿可复位积分器的输出，得到本发明的反馈量逆控制规律是式(5)所表示的控制规律，其输出td是全控型开关S1和S4在一个PWM开关周期内导通的时间；td与开关频率相乘后得到的对应的占空比与恒定频率三角波进行比较，得到PWM输出脉冲，去驱动和控制装置全控开关的开通与关断，产生电流i_c。通过这样的闭环调节，可以使得装置的输出电流i_c跟随任意波形参考信号i_ref，并具有很快的动态响应速度和很高的补偿精度。具体步骤如下：As shown in Figure 1, S1-S4 are full-control switches connected to form a single-phase full bridge. The switches are connected with resistance-capacitance absorption circuits and anti-parallel diodes. I _c is the output current of the device, and u _dc is the capacitor voltage of the DC side. u _s is the AC power supply voltage, L is the reactor for connecting the device to the power grid, and the load is a commonly used thyristor rectifier load. Using the triangular wave carrier shown in Figure 2, the full-control switches S1 and S4 are turned on at T-td/2, and turned off at T+td/2, while the full-control switches S2 and S3 are opposite. The principle of the available reverse control current tracking method based on average current compensation is shown in Figure 3. In Fig. 3, i _ref is a given arbitrary waveform reference signal;

is the feedback quantity adopted by the present invention; the inverter is the power electronic device shown in Fig. 1, i _c is the output current of the device, u _dc is the capacitor voltage of the DC side of the device, and u _s is the AC power supply voltage of the device; Reset integrator, it resets once every PWM switching cycle, like this, the output of resettable integrator is exactly the average value of _i in a PWM switching cycle; The average current model is the average current model of the device represented by formula (4); Z-1 means that the signal is delayed by one PWM switching cycle than the current time, so that the output of the average current model can be obtained twice before and after, and their difference is used to compensate the output of the resettable integrator, and the feedback amount of the present invention is obtained The inverse control law is the control law represented by formula (5), and its output td is the conduction time of the fully-controlled switches S1 and S4 in a PWM switching cycle; the corresponding duty ratio obtained by multiplying td with the switching frequency Compared with the constant frequency triangular wave, the PWM output pulse is obtained to drive and control the on and off of the full control switch of the device, and generate the current _ic . Through such closed-loop adjustment, the output current _ic of the device can be made to follow the arbitrary waveform reference signal i _ref , and has fast dynamic response speed and high compensation precision. Specific steps are as follows:

1. The measurement signal is output through a resettable integrator, and the average value of the measurement signal within one PWM period is obtained.

2. Establish the average current model of the device.

According to the turn-on and turn-off of each fully-controlled switch, the relationship between the output current of the device and the input voltage can be obtained, and the average current model of the device shown in formula (4) can be derived.

3. The output of the measurement signal i _c is added to the output of the resettable integrator and the difference between the two times before and after the average current model to obtain the feedback quantity

4. According to the inverse control law shown in formula (5), the conduction time td of the full-control switches S1 and S4 in one PWM cycle is obtained, and td is the output of the controller.

5. The output td of the controller is multiplied by the switching frequency to obtain the corresponding duty ratio. The duty ratio is compared with the fixed frequency PWM carrier to obtain the PWM output pulse, which drives and controls the on and off of the full control switch, thereby controlling the power The output waveform of the electronics quickly and precisely tracks the reference signal.

Finally, the power supply current can quickly and accurately track the sinusoidal reference signal.

As shown in Figure 4 and Figure 5, the current tracking waveform is obtained, IL is the load current waveform, Ir is the sinusoidal reference signal, and Ia is the power supply current waveform.

Claims (4)

1. contrary Control current tracking and controlling method based on average current compensation is characterized in that concrete steps are as follows:

1) measuring-signal is exported through resetting integrator, and the every PWM switch periods of resetting integrator resets once, and its output then is that measuring-signal is at the mean value of a PWM in the cycle;

2) apparatus for establishing average current model, the difference of obtaining the output of former and later two PWM switch periods of average current model is by way of compensation;

3) feedback quantity of k PWM switch periods of calculating, this feedback quantity is obtained through the output of resetting integrator and the difference addition of former and later two PWM switch periods outputs of average current model by measuring-signal;

4) by the transient current recurrence relation of installing, promptly the device of k+1 PWM switch periods of the device of k PWM switch periods output transient current recursion is exported the relation of transient current, the backstepping control law, the output of controlled device---control the ON time of switch entirely;

5) carrier wave that adopts the constant frequency triangular wave to follow the tracks of as PWM, the duty ratio that the constant frequency triangular wave is corresponding with the output of controller is compared, and is driven and control the pwm pulse that full control switch is opened and turn-offed.

2. the contrary Control current tracking and controlling method based on the average current compensation as claimed in claim 1, it is characterized in that, described apparatus for establishing average current model is meant: when the full control switch conduction of power electronic equipment with when turn-offing, according to flowing through the electric current that device inserts the electrical network reactor, list the transient state relation of device output current and supply voltage and dc capacitor voltage, when a pair of diagonal is wherein controlled switch conduction entirely, when other turn-offed, the pass of device output current and supply voltage and dc capacitor voltage was:

$i_c(\mathrm{kT}+\mathrm{td})=\frac{u_{\mathrm{dc}}-u_s}{L}\mathrm{td}+i_c\left(\mathrm{kT}\right)$ ?k＝0，1，2，…，+∞(1)

Wherein, i _cBe the device output current, u _DcBe dc capacitor voltage, u _sBe AC supply voltage, L is the reactance value that device inserts the reactor of electrical network, and T is the PWM switch periods of device, and td is the ON time of that a pair of full control switch in a PWM switch periods; When another controls switch conduction entirely to diagonal, when other turn-offed, the pass of device output current and supply voltage and dc capacitor voltage was:

$i_c(\mathrm{kT}+T-\mathrm{td})=-\frac{u_{\mathrm{dc}}+u_s}{L}(T-\mathrm{td})+i_c(\mathrm{kT}+\mathrm{td})---\left(2\right)$

With formula (1) substitution formula (2), the transient current recurrence relation that can install is:

$i_c(\mathrm{kT}+T)=\frac{u_{\mathrm{dc}}\left(\mathrm{kT}\right)}{L}[2\mathrm{td}\left(\mathrm{kT}\right)-T]-\frac{u_s\left(\mathrm{kT}\right)}{L}T+i_c\left(\mathrm{kT}\right)---\left(3\right)$

Formula (1) and formula (2) are asked on average a PWM switch periods integrates, can be got the average current model of auto levelizer:

$\stackrel{\&OverBar;}{i_c}\left(\mathrm{kT}\right)=i_c\left(\mathrm{kT}\right)+\frac{-2u_{\mathrm{dc}}\left(\mathrm{kT}\right){[T-\mathrm{td}\left(\mathrm{kT}\right)]}^2+[u_{\mathrm{dc}}\left(\mathrm{kT}\right)-u_s\left(\mathrm{kT}\right)]T^2}{2\mathrm{LT}}---\left(4\right)$

Wherein, i _cIt is the average current of device in the PWM switch periods.

3. the contrary Control current tracking and controlling method based on the average current compensation as claimed in claim 2, it is characterized in that, described backstepping control law is controlled the ON time of switch entirely, and its method is: with the device output transient current i of k+1 PWM switch periods in the transient current recurrence relation _c(kT+T) use reference signal i _Ref(kT+T) replace the device output transient current i of k PWM switch periods _c(kT) with the feedback quantity of k PWM switch periods

Replace, and backstepping controls switch conduction time td entirely, can get control law and be:

$\mathrm{td}(\mathrm{kT}+T)=\{[i_{\mathrm{ref}}(\mathrm{kT}+T)-{\hat{i}}_c\left(\mathrm{kT}\right)]\frac{L}{T}+u_s\left(\mathrm{kT}\right)+u_{\mathrm{dc}}\left(\mathrm{kT}\right)\}\frac{T}{2u_{\mathrm{dc}}\left(\mathrm{kT}\right)}---\left(5\right).$

4. the contrary Control current tracking and controlling method based on average current compensation as claimed in claim 1 is characterized in that the duty ratio of the output correspondence of described controller is meant: the multiply each other numerical value of gained of the output of controller and switching frequency.

Images