JPH10337034A - Constant sampling current control system for sine wave input single phase rectifier circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a switching algorithm for substantially bringing the power factor of input current to 1 in a mixed bridge circuit. SOLUTION: The single phase rectifier circuit comprises a mixed bridge comprising two active elements X, Y and a smoothing capacitor CD, and a single phase AC system linked with the mixed bridge wherein an error function between the actual AC current at a linking point and a target function of sine wave current is derived by detecting the actual AC current at a constant sampling period and comparing with the target function. Based on the value of a target function obtained at each sampling time and each value of current error, a switching mode is selected for each main element X, Y of the mixed bridge after a specified control time and the mixed bridge is operated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a constant sampling type current control system for a sine wave input single-phase rectifier circuit used as a DC power supply.

[0002]

2. Description of the Related Art In many cases, a DC power supply is used in home electric appliances and communication equipment. In order to obtain DC from commercial AC, recently, a rectifier circuit using a semiconductor, especially a PWM method for a mixed bridge circuit has been used. ing. In this case, since the home electric appliance and the industrial power supply are the harmonic generation sources, it is expected that the input current is converted into a sine wave. As this type of system, a triangular wave comparison system shown in FIG. 7A and a hysteresis comparator system shown in FIG. 7B have been proposed.

FIG. 7 (a) shows a journal of the Institute of Electrical Engineers of England (I
EE PROCEEDINGS-B, Vol. 138,
No. 5, SEPTEMBER 1991) "Nove
lful bridge semicontrol
ed switch mode rectifier ”
by S.I. The current error Δ (t) = i (t) −j (t) is compared with the triangular carrier wave, and the connection point voltage v _t between the AC system and the AC / DC converter is described in Manias (FIG. 7). When (t) satisfies the following conditions, an ON operation command is issued to each of the corresponding switching gates. That is, v
_{When t} (t) ≧ 0, the X gate issues an operation command to the gate, and when v _t (t) <0, issues an operation command to the Y gate.

FIG. 7 (b) shows a journal of the Institute of Electrical Engineers of Japan (T. IEEE J.).
apan, Vol. 115-D, no. 2, 1995)
FIG. 1 of “Reduction of Capacitor Capacity of Half-Bridge PWM Converter” shows that the carrier wave comparison part in FIG. 7A is replaced with a hysteresis comparator indicated by a dotted line, and the other parts are the same. is there.

[0005]

As described above, various control systems using a main circuit as a mixed bridge have been proposed, but it has been pointed out that there is a possibility that waveform distortion may occur. Not guaranteed. In addition, Heisei 6
With the introduction of harmonic guidelines by the Agency for Natural Resources and Energy on September 30, 1998, a switching rectifier (Switch) that generates less harmonics and is simple and easy to handle
Expectations for Mode Rectifier are increasing.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and in a mixed bridge circuit, a constant sampling type current of a sine wave input single-phase rectifier circuit capable of achieving a switching algorithm with an input current of approximately a power factor of 1. It is intended to provide a control method.

[0007]

According to a first aspect of the present invention, there is provided a constant sampling type current control system for a sine wave input single-phase rectifier circuit, comprising: a mixing bridge comprising two active elements and a smoothing capacitor; In a single-phase rectifier circuit composed of a single-phase AC system interconnected with a mixing bridge, an actual AC current at the interconnection point is detected at predetermined fixed sampling periods and compared with a target function based on a sine wave current. An error function of the difference between the actual AC current and the target function is derived by using the mixed bridge after a predetermined control time based on the value of the target function and the value of the current error obtained at each sampling time. The switching mode of each main element is selected to operate.

According to a constant sampling type current control method for a sine wave input single-phase rectifier circuit according to claim 1 of the present invention, an actual AC current at an interconnection point is detected at a constant sampling period, and the sine wave current is used. Compare with the objective function. In this case, the difference between the interconnection point current and the target current is derived as an error function, and control is performed so that the interconnection point current follows the target function as the command value according to the sign of the error function. The switching mode of the mixed bridge is as shown in Table 1.

[Table 1]

According to a second aspect of the present invention, there is provided a constant sampling type current control system for a sine wave input single-phase rectifier circuit according to the first aspect, wherein the DC voltage source is a secondary battery and its size is V _D. when a and configured to meet the V _D> * 2E _a. Here, VD is the voltage value of the DC voltage source. E _A : RMS value of AC voltage on the grid side. *: Indicates the root symbol of the mathematical formula (the same applies hereinafter).

[0010] Constant-sampled current control method of the sine wave input, single-phase rectifier circuit according to the claim 2 of the present invention are the step-up rectifier, consider only the case of V _D> * 2E _A.

[0011] Constant-sampled current control method of the sine wave input, single-phase rectifier circuit according to the claim 3 of the present invention, in [claim 1], the inductance L _P of the rectifier device, the sampling period T _S, the control delay time T _C is configured to satisfy the following condition so.

(Equation 1)

[0012] Constant-sampled current control method of the sine wave input, single-phase rectifier circuit according to the claim 3 of the present invention, to improve the followability of the current defines the lower limit on the inductance L _P within the rectifier In addition, the upper and lower limits of T _S + T _C , which is the sum of the sampling period T _S and the control delay time T _C , are defined. If this exceeds the upper limit, it is not guaranteed that the current tracking error will be within the target tracking error width j (e).

According to a fourth aspect of the present invention, a constant sampling type current control method for a sine wave input single-phase rectifier circuit according to the first aspect of the present invention is arranged such that the current command j (t) as a target function is expressed by the following equation. It was configured to meet.

(Equation 2)

According to a fourth aspect of the present invention, there is provided a sine-wave input single-phase rectifier circuit having a constant sampling type current control method, wherein the current command condition is such that the DC output voltage E of the rectifier circuit (mixed bridge) is set. _This is for controlling _D [V] to be _VD [V].

According to a fifth aspect of the present invention, there is provided a constant sampling type current control system for a sine-wave input single-phase rectifier circuit, wherein a mixed bridge comprising two active elements and a smoothing capacitor is connected to the mixed bridge. In a single-phase rectifier circuit composed of a single-phase AC system, the actual AC current at the interconnection point is detected and compared with a target function j (t) based on a sine wave current, thereby obtaining a difference between the actual AC current and the target function. First comparing means for deriving an error function Δ (t) of the target function j (t)
(t) ≧ 0, j (t) <0, comparing the error function Δ (t) from the first comparing means with the carrier wave from the carrier generating means, a first output means for turning on the main element X of the mixing bridge when (t) ≦ the carrier wave and a target function j (t) ≧ 0 from the second comparison means; The error function Δ (t) is compared with the carrier wave from the carrier generation means, and the Δ (t) carrier wave and the target function j (t) <from the second comparison means are compared.
Second output means for turning on the main element Y of the mixing bridge when the value is 0.

A constant sampling type current control method for a sine wave input single-phase rectifier circuit according to claim 5 of the present invention is realized by comparing carrier waves. Therefore, unlike what is described in [Claim 1] to [Claim 4],
Not a constant sampling method. The switching algorithm in Table 1 is the same even in the case of comparison with a carrier wave such as a triangular wave.

[0017]

FIG. 1 is a block diagram showing an embodiment of a current control system for a sine wave input single-phase rectifier circuit according to the present invention. In FIG. 1, the left side from point A indicates the AC system side,
e _A (t) is an alternating voltage, L _S is the inductance of the system, i _P (t) is the AC current value of the interconnection point, the C _D is a smoothing capacitor. Right of point B indicates the outside of the apparatus, L _P is the inductance in the rectifier device, I _D (t) is the load current value, v
(t) is the switching voltage.

[0018] in the main circuit X, Y diode D _X with respect to each a main element of controllable, D _Y together with connected in parallel, the diode D in series with each to each main element
_U, constitute a hybrid bridge connected in parallel to those connecting the D _V in series. That is, a bridge connection having controllable and non-controllable main arms is employed. Where C
_D is a smoothing capacitor, but it can be used even if this is not a capacitor but a secondary battery. However, in the case of a secondary battery, it is not installed outside the device.

1 is a pulse width modulator and a pulse generator 2
It operates in response to a sampling pulse from. here,
Let the target function j (t) be an arbitrary function, and determine whether the difference Δ (t) (error signal) from the alternating current value i _P (t) at the interconnection point of the main circuit is within the target tracking range, at a constant sampling cycle. It is intended to control the alternating current value i _P (t) at the interconnection point within a predetermined range by selecting the switching mode of the mixed bridge composed of semiconductor elements when the deviation is out of the error range. .

The pulse width modulator 1 operates at each sampling time t
_n (t _n −t _n-1 = T _s : const), the target function j
(t _n ) and the value of the current error Δ (t _n ) (≡i (t _n ) −j (t _n )) are read, and t after the control delay time T _C (T _C ≦ T _S )
at _n + t _c, and outputs a gate command to the main element of the mixed bridge according to the table.

The target function j (t) is a sine wave having a power factor of 1 or a delay, and in the case of a rectifier, is created by the block diagram shown in FIG. In this case, the load current at time t is represented by I _D (t) [A]
, And the set value of the DC voltage is V _D [V]. Note that we consider only the case of V _D> * 2E _A here. Therefore, the rectifier here is a step-up rectifier. Also, the interconnection point current i
_Let the target power factor angle of _P (t) be θ [rad]. However, π / 2 ≧
θ> 0.

First, at 24 and 25, the voltage phase of the power receiving point is detected by a PLL or the like, and the detected voltage phase is used to detect * 2 sin at 28.
A voltage of (ωt−θ) [V] is created. Make V _D -E _D from 21 and 22, via the first-order lag circuit 26 (V _D
-E _D) to create a _{× K / (1 + T 1} S). 21 and 2
3 and V _D · I _D are generated through the primary delay circuit 27
Create _D · I _D / E _A cos (1 + T ₂ S).

The following target function j (t) is created from the above.

(Equation 3) K and K 'are gains, and T ₁ and T ₂ are time constants.
Here, the feedback term is a feedforward term.

As described above, the pulse modulator 1 is of a constant sampling type (the sampling period is T _S [S]), and its basic function is to set the interconnection point current i _P (t) to a target value which is a command value. That is, control is performed so as to follow the function j (t).

Here, the performance of the pulse modulator is such that the interconnection point current i _P (t) follows the target function j (t) ± j _e [A] if the following conditions are satisfied. Is logically guaranteed to follow within the range. Since these logical proofs are not the object of the present invention, they are omitted, and instead of the proofs of the above conditional expressions, since the experimental results performed in the embodiments described later match the theoretical values obtained by the above mathematical expressions. Incidentally, j _e can be the target value of the tracking error range, it is set to any value.

[0026] Conditions As already mentioned, the E _D> * 2E _A. Condition: The operation of the gate based on the above table, that is, at an arbitrary sampling time t _n , the target function j (t _n ) and the current error Δ (t _n ) are read, and at time t _n + T _C , A gate command for the main elements X and Y is issued.

[0027] The value of the inductance L _P of the conditions rectifier, to satisfy the following inequality. Here, the target function j (t) = * 2I _A sin (ωt−θ) [A], and j
_e [A] is the target tracking error width as described above.

(Equation 4)

The condition sampling period T _S [S] and the control delay time T _C [S] are determined so as to satisfy the following inequalities. Note that L _S is the inductance of the system.

(Equation 5)

The meaning of setting the above conditions will be qualitatively described below. First, the condition means that the rectifier is limited to the boost type. The condition means that the central part of the present invention is a constant sampling type pulse modulator.

The condition is the inductance L _P in the rectifier.
The upper and lower limits are set. That is, if the value of L _P is too large, the magnitude of di _P / dt becomes small, and the current follow-up property is deteriorated. On the other hand, if L _P is too small, the receiving voltage is around 0 V and the connection point current i _{This is because P} (t) falls early to 0, causing an error with respect to the target function j (t) which is a delayed power factor.

[0031] Conditions intended to define the upper limit of T _S + T _C, it exceeds the upper limit, because the be current tracking error is within j _e no longer be guaranteed.

When the above conditions (1) and (2) are satisfied at the same time, it is understood that the following effects (a) and (b) of the rectifier can be guaranteed theoretically and experimentally.

(A) If | Δ (t _n + T _C ) | ≦ j _{e at a} certain switching time t _n + T _C , t _n + T _C ≦ t
At an arbitrary time t, | Δ (t) | ≦ j _e . This means that the tracking error width is guaranteed. (B) When the device is started, | Δ (t _n + T _C ) | ≦ j _e is automatically satisfied at a certain switching time t _n + T _C. This means that the automatic following has been started. For these, the mathematical proof is omitted as described above.

[0034] In any case, the above (i), (ii), when you start the device, automatically initiates a following of within the target range of error j _e to the target function j (t), also target Even if the sine wave, which is a function, changes during operation, the control automatically starts following a new target, thus enabling stable control.

Next, the overall operation will be described. In the target function (current command) Here, j (t) = * 2I A sin (ωt-
θ) [A], θ is the power factor angle, and ω is the system angular frequency. or,
Constant sampling period T _S [S], each sampling time t
_{0, t 1, ..., t} n, t n-1 (t k -t k-1 = T S: co
nst), interconnection point current i _P (t), interconnection point error function Δ (t) ≡
i (t) -j (t) , the response delay time _{T C (T C ≦ T S} ).

First, the actual AC current i at the interconnection point of the main circuit
_P (t) is detected, a difference Δ (t) from j (t) which is a target function is obtained, and j (t) and Δ (t) are input to the pulse width modulator 1. The pulse from the pulse generator 2 is input to the pulse width modulator. Note that entered the target tracking error signal j _e predetermined for the pulse width modulator. Here, the target tracking error signal, means set margin limits the width as a target function j (t) ± j _e.

[Calculation Examples] Calculation examples for [Claim 1] to [Claim 4] will be described below. Calculation Example 1 An example in which [Claim 1] to [Claim 3] are used simultaneously is shown. DC 1 that receives power from a 100 V, 50 Hz commercial system
For a rectifier of 80V, 200W, the target power factor is 0.99 with a delay, and the value of L _S representing the short-circuit capacity at the receiving point is 2
% L _S = 3 mH (1.9%).

The active power P and the reactive power Q at the receiving point are P = 200 when the loss of the switch and the diode is ignored.
Since W and Q = 28.5 Var, the target function j (t) is given by equation (1). It should be noted that I _A = 2.02 _A , θ = 8.6.
5 °.

J (t) = 2.02 * 2 sin (100πt−8.65 °) [A] (1)

The target value j _e of the tracking error width is set to j _e = 0.
4A (14% of the amplitude of i (t)). Values between L _P is from the method of [Claim 3], should satisfy the inequality shown below (2). When the equation (2) is calculated, the equation (3) may be used.

(Equation 7)

The values of T _S and T _C may also satisfy the inequality of the following equation (4) from the method of claim 3.
Here, T _S = 20 μs and T _C =
Select 15 μs.

(Equation 8)

FIG. 3 is a simulation result of the interconnection point current and the current error by the computer. In FIG. 3, the horizontal axis represents time [ms] and the vertical axis represents current [A]. FIG. 3 shows a state at the time of starting at t = 5 ms. The interconnection point current i _P (t) properly follows the target function j (t), and the current error after the starting is, | Δ (t) | ≦
It can be seen that is the j _e = 0.4A.

FIG. 4 is a diagram showing a gate command.
Here, the horizontal axis represents time [ms], and the vertical axis represents voltage [V]. The upper side is an X gate, and the lower side is a Y gate. Here, the voltage value means a switching voltage. As shown in FIG. 4, the average switching frequency is 3.6 kHz, and a command is issued approximately once every seven times.

Calculation Example 2 Next, a calculation example using [Claim 1] to [Claim 4] simultaneously will be described. Receive power from 100V, 50Hz system d.
c. 180V, 200W rectifier, main circuit and PW
The M control method is the same as the calculation example 1. The DC voltage control method according to the invention of claim 4 is incorporated,
C _D than the capacitor of the DC side by a known method, C _D
= 500 μF (from the target that the DC voltage fluctuation is within 2%).

The current command j (t) is expressed by equation (6), and K = 0.
05, T ₁ = 2 ms, T ₂ = 2 ms. Note that V _D
Is 180 [V] as described above.

(Equation 9)

FIG. 5 shows changes in the interconnection point current, voltage and DC voltage when the DC load suddenly changes from the rated 200 W to 1/20 of 10 W during operation at a DC voltage of 180 V. It is a diagram simulated with changes,
The horizontal axis represents time [ms] and the vertical axis represents voltage [V].

As can be seen from FIG. 5, even if the DC power is instantaneously reduced from 200 W to 10 W to 1/20 at a time of 40 ms, the DC voltage is kept almost constant, and the input AC current waveform It can be seen that the sine wave is maintained. The control is extremely stable on both the DC and AC sides.

As shown in the calculation examples and the simulation by the computer, it can be seen that the theoretical value and the simulation almost coincide. Therefore, the present invention has been proved to be extremely useful because it complies with the previously described harmonic guidelines of the Agency for Natural Resources and Energy.

In the above embodiment, digital control with a fixed sampling period has been described. However, the present invention is not limited to this, and an analog system may be used. In this case, the switching algorithm in Table 1 may be executed by comparison with a carrier wave such as a triangular wave.

FIG. 6 is a block diagram showing an embodiment of the analog system. In FIG. 6, reference numeral 61 denotes a first comparator for generating a current error Δ (t). That is, a current error Δ (t) is created from the actual AC current i _P (t) and the target function (command current) j (t). 62 is a second comparator, which is the sign j (t) of the objective function.
It is determined whether ≧ 0 or j (t) <0.

Reference numeral 63 denotes a third comparator to which the current error Δ (t) from the first comparator is inputted and a triangular wave or the like from the carrier generator is inputted. Reference numeral 64 denotes a fourth comparator to which Δ (t) from the first comparator 61 and a triangular wave from the carrier generator are input. Incidentally, reference numeral 65 denotes a NOT circuit.

The input from the second comparator 62 and the input from the third comparator 63 are introduced into the X gate, and
An ON command is issued when (t) ≦ carrier wave and j (t) ≧ 0, and otherwise, the X gate is OFF. The Y gate receives the inverted output of the second comparator 62 and the input of the fourth comparator 64, so that Δ (t)> carrier wave and j (t) <.
ON command when 0, Y gate OFF otherwise
It is.

As described above, even with the analog system shown in FIG. 6, it is possible to issue an operation command to the main element of the above-mentioned mixing bridge and to operate it.
The configuration of the X and Y gates (mixed bridge) is omitted.

Further, the objective function j (t) shown in [Claim 4]
Is applied not only to the main circuit of the mixed bridge, but also to a general full-bridge rectifier circuit. Here, since the full bridge itself is a known one, detailed description is omitted.

Note that the rectifier circuit described above includes a power supply circuit for home electric appliances (TV, air conditioner, etc.), a communication power supply, a single-phase UPS.
(Uninteractive Power Sour
ce) can be applied to a wide range of applications such as input converters and other various DC power supply devices.

[0055]

As described above, according to the present invention, even in a single-phase rectifier circuit using a mixed bridge, it is possible to provide a control method which can sufficiently fall within the target tracking error range. is there.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of a constant sampling type current control system of a sine wave input single-phase rectifier circuit according to the present invention.

FIG. 2 is a block diagram for creating a target function for controlling a DC voltage.

FIG. 3 is a simulation diagram by a computer showing a state where an interconnection point current follows a target function.

FIG. 4 is a diagram showing a gate command.

FIG. 5 is a diagram showing changes in the interconnection point current, voltage, and DC voltage when the DC load power changes suddenly.

FIG. 6 is a configuration diagram showing an embodiment of an analog system.

FIG. 7 is a diagram illustrating a conventional device using a mixing bridge.

[Explanation of symbols]

 Reference Signs List 1 pulse width modulator 2 pulse generator 61-64 comparator

Claims (5)

[Claims] In a single-phase rectifier circuit comprising a mixed bridge composed of two active elements and a smoothing capacitor, and a single-phase AC system interconnected with the mixed bridge, the single-phase rectifier circuit is provided at predetermined fixed sampling periods. An error function of the difference between the actual AC current and the target function is derived by detecting the actual AC current at the system point and comparing it with the target function based on the sine wave current, and at each sampling time, the error function of the target function obtained at the time is obtained. A constant sampling type current of a sine wave input single-phase rectifier circuit, wherein the switching mode of each main element of the mixing bridge is selected and operated after a predetermined control time based on each value of the value and the current error. control method. 2. A constant sampling type current control method for a sine wave input single-phase rectifier circuit according to claim 1, wherein the DC voltage source is a secondary battery, and when its size is V _D , V _D > *
_A constant sampling type current control method for a sine wave input single-phase rectifier circuit characterized by 2EA. Here, VD is the voltage value of the DC voltage source. E _A : RMS value of AC voltage on the grid side. *: Indicates the root symbol of the mathematical formula (the same applies hereinafter). 3. A constant sampling type current control method for a sine wave input single-phase rectifier circuit according to claim 1, wherein an inductance L _P , a sampling period T _S , and a control delay time T _C in the rectifier satisfy the following conditions. A constant sampling type current control method for a sine wave input single-phase rectifier circuit, characterized in that: (Equation 1) 4. A sine-wave input single-phase rectifier circuit according to claim 1, wherein the current command j (t) as a target function satisfies the following equation. Constant sampling type current control method of phase rectifier circuit. (Equation 2) 5. In a single-phase rectifier circuit comprising a mixed bridge composed of two active elements and a smoothing capacitor, and a single-phase AC system connected to the mixed bridge, an actual AC current at the connection point is detected. Target function j (t) by sinusoidal current
A first comparing means for deriving an error function Δ (t) of a difference between the actual AC current and the target function by comparing with the sign j (t) ≧ 0, j ( t) The second comparing means for determining <0, the error function Δ (t) from the first comparing means and the carrier wave from the carrier generating means are compared, and Δ (t) ≦ carrier wave and First output means for turning on the main element X of the mixing bridge when the target function j (t) ≧ 0 from the second comparison means; and an error function Δ (t) from the first comparison means and Comparing the carrier wave from the carrier generation means, and turning on the main element Y of the mixing bridge when the carrier wave is Δ (t) and the target function j (t) <0 from the second comparison means. A constant sampling type current control system for a sine wave input single-phase rectifier circuit, comprising: an output unit.