JPH01298959A - Pwm converter - Google Patents

Abstract

PURPOSE:To reduce harmonic waves by providing a phase difference calculator, an adder, and a phase comparator, and adding a voltage correction signal to a voltage command value. CONSTITUTION:A PWM converter is composed of an AC power source 1, a reactor 2, a power converter 3, a smoothing capacitor 4, a voltage detector 5 and a load 6. Further, a current detector 7, a phase detector 8, a coordinates converter 9, an orthogonal component current setter 10, a subtractor 11, a current controller 12, a DC voltage setter 13, a voltage controller 15, a current controller 17, a coordinates converter 18, and 3 PWM signal forming circuits 19-21 are provided. For example, a phase comparator 22A discriminates the polarity of an output current I on the basis of a current phase, a phase difference calculator 30 calculates the phase difference of the current I, and adders 31-33 add the phase difference to the voltage phases of the phases, and output it. Thus, a regulator 23 can add a voltage correction signal of the polarity corresponding to that of the output current Iw to the voltage command value, and accurately controls it.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention provides a PW for turning on a switching element.
This invention relates to a PWM converter device that converts alternating current power to direct current power by controlling the pulse width of the M signal, and particularly relates to a P'WM converter device that performs power conversion with high precision without being affected by ripples in the output current. be.

[Prior Art] FIG. 3 is a block diagram showing a conventional PWM converter device using a PWM inverter described in, for example, Japanese Unexamined Patent Publication No. 60-229676.

In the figure, an AC power source (1) supplies three-phase AC power of U phase, V phase, and W phase, and a reactor (2) is connected to the supply terminal of each phase.

The power converter (3) consists of a plurality of transistors (switching elements) (3a) to (3f) and diodes (rectifiers) (3g) to (:H), and the transistor (3a)
The connection points of each pair of ~ (3f) and diodes (3g) ~ (31) are connected to the AC power supply (1) via the reactor (2).
connected to the supply terminal. And PWM, which will be described later
The AC power supply (1) is activated by the PWM signal from the signal generation circuit.
The AC power supplied from the AC power source is converted into the desired DC power.

A smoothing capacitor (4) that outputs an averaged DC voltage Ed is connected between both ends of the transistor pair and diode pair of the power converter (3). , voltage detector (5) and load (6
) are connected.

A current detector is provided between the reactor (2) and the power converter (3) to detect three-phase AC output currents 1u, Iv, and Ill flowing from the power converter (3) to the AC power source (1). (7) is provided at the supply terminal of the AC power source (1), and a phase detector (8) for detecting each voltage phase θBu, θBv, and 06w of the three-phase AC voltages Eu, Ev, and EIll is provided. is connected.

The coordinate transformer IQ (9) transforms the output currents Iu, Iv, and Iu+ into reactive current Id and active current IQ of two orthogonal axes based on voltage phases θr, u, θHv and θP, w.

The reactive current setting circuit (10) outputs a reactive current setting value Id'' corresponding to the reactive current 1d, and the subtracter (11) subtracts the reactive current Id from the reactive current setting value Id'''. ) outputs an invalid voltage setting value Vd'' based on the difference current signal from the subtracter (11).

The DC voltage setting circuit (13) outputs a voltage setting value Ed'' corresponding to the DC voltage Ed, the subtracter (14) subtracts the DC voltage Ed from the voltage setting value Ed'', and the voltage controller (15)
outputs an effective current set value Iq1 corresponding to the effective current 1q based on the differential voltage signal from the subtracter (14). The subtracter (16) subtracts the effective current Iq from the effective current setting value Iq8, and the current controller (17) subtracts the active current Iq from the effective current setting value Iq8.
The effective voltage set value ql' is output based on the differential current signal from the .

A coordinate converter (18) connected to the current controllers (12) and (17) converts the reactive voltage setting value Vd" and the effective voltage setting value of the orthogonal two axes based on the voltage phases θεU, θEV, and θB- q'' is converted into three-phase voltage command values Vu'', Vv'', and Vw.

The three PWM signal generation circuits (19) to (21) each consist of the same components, and each voltage command value Vu'', Vv
PWM signal Pa having a pulse width according to ' and Vw'
~Pf is output.

For example, the W-phase PWM signal generation circuit (21) includes a comparator (22) that determines the polarity of the output current In, and a comparator (22) that determines the polarity of the output current In.
22) according to the output signal of rectangular waveform voltage correction signal Δ■
an adder (24) that adds a voltage correction signal Δ■ to the voltage command value Vw'', a carrier wave generator (25) that outputs a triangular carrier wave Vc, and an adder (23) that outputs a triangular carrier wave Vc. 24), a subtracter (26) that subtracts the carrier wave Vc from the voltage command value Vw'' corrected by the comparator (26) that outputs ON signals Q and Q in accordance with the output signal of the subtracter (26).
7), a delay element (28) that delays the rising timing of the on signals Q and Q by a time proportional to the voltage correction signal Δ■, and outputs the result as PWM signals Pe and Pf;
29).

Next, while referring to the waveform diagrams in FIGS. 4 and 5,
The operation of the conventional PWM converter device shown in the figure will be explained.

The current detector (7) detects the output currents 1u, Iv, and I-, and connects the coordinate converter (9) and the PWM signal generation circuit (1
9) Input in (21). Moreover, the phase detector (8) is
Voltage phase θBu of AC voltages E u, E v and EIll
, θEEV and θHm are detected and input to coordinate converters (9) and (18). Each voltage phase θEu, θBv and θ
EIll is expressed as θpu-θ θRV-θ-(2/3)π θ口4=θ+(2/3)π.

The coordinate converter (9) converts AC voltages Eu, Ev and E-
The orthogonal component (reactive current) Id with respect to the power supply voltage E and the in-phase component (active current Hq are calculated from ... ■. Through this calculation, the reactive current Id and the active current IQ are converted into DC amounts.

On the other hand, the reactive current setting value Td' generated from the reactive current setting circuit (10) is converted to the reactive current Id by the subtracter (11).
is subtracted to form a difference current signal, which is input to the current controller (12). The current controller (12) performs, for example, a proportional integral calculation on the difference current signal, and sets voltage command values Vu'', Vv' and ■1.
The orthogonal component (reactive voltage command value) Vd'' with respect to the power supply voltage E of the voltage command value 1 corresponding to the DC amount of is output.

Further, the voltage setting value Ed" generated by the DC voltage setting circuit (13) is subtracted by the DC voltage Ed by the -I & calculator (14) to become a differential voltage signal, which is input to the voltage controller (15). The voltage controller (15) performs, for example, a proportional-integral operation on the differential voltage signal, and outputs an effective current setting value ■q1 of the output current ■, which is an in-phase component when the power supply voltage E is referenced.This effective current setting From the value Iq8, the effective current IQ is subtracted by the subtracter (16), and the resulting difference current signal is input to the current controller (17). Then, the in-phase component of the voltage command value V8 with respect to the power supply voltage E (effective voltage setting value) VQ''' is output.

The coordinate converter (18) converts the three-phase AC voltage command value V based on the invalid voltage setting value Vd' and the effective voltage setting value ■q1.
u', Vv' and VW'' are calculated from ...■. Through this calculation, the reactive voltage setting value Vd'' and the effective voltage setting value vq8 corresponding to the DC amount are determined as the voltage command value Vu'' of the AC amount, Vv'' and Vw'' and input to each PWM signal generation circuit (19) to (21).

Here, focusing on the W-phase PWM signal generation circuit (21),
The case where the voltage correction signal Δ■ is zero will be explained. A subtracter (26) subtracts the carrier wave Vc from the voltage command value Vw'', and the resultant voltage command value Vw'' is input to a comparator (27).

Based on the output signal of the subtracter (26), the comparator (27) calculates the voltage command value Vw'' and the carrier wave Vc as shown in FIG.
When Vll'>Vc, an on signal Q is output, and when Vw''<Vc, an on signal is output. These on signals Q and Q are connected to the delay elements (28) and (29). ), the rise timing is delayed by transistors (3e) and (3
) are output as PWM signals Pe and Pf for turning on the delay elements (28) and (29), respectively.
) prevents an arm short circuit caused by a delay in turning off the l transistors (3c) and (3r).

Transistor (3e) by PWM signals Pe and Pl
and (3r) are controlled to be turned on alternately, and an alternating current output voltage Vw is generated from both ends of the transistor pair. This output voltage - is averaged by a smoothing capacitor (4) and applied to a load (6) as a desired DC voltage Ed corresponding to the voltage setting value Ed'.

At this time, the output voltage - includes a voltage no-control period Td corresponding to a delay time, and this voltage no-control period Td occurs twice during one cycle of the carrier wave Vc.

Therefore, in one cycle of the carrier wave Vc, the ratio of the voltage non-control period Td to the output voltage - is k = 2, where the time of one cycle of the carrier wave Vc is Tc.
It is expressed as T d/T c . For example, when the frequency of the carrier wave Vc is 2500)1z and the voltage no-control period Td is 50 μsec, k is 0.25. Since the output voltage Vw during this voltage non-control period Td is influenced by the polarity of the output current I, it is necessary to correct the voltage command value Vw'' according to the polarity of the output current ■.

Therefore, the comparator (22) determines the polarity of the output current 1u+, and if the polarity is positive, a positive output signal is input to the regulator (23), and if the polarity is negative, a negative output signal is input to the regulator (23). As a result, the regulator (23) outputs the voltage correction signal ΔV, but the value of the voltage correction signal Δ■ is -0, 25 as described above, approximately 25% of the peak value of the carrier wave Vc. Set.

FIG. 5 is a waveform diagram when k is 0.25 and the voltage command value Vw'' is zero to simplify the explanation. In the figure, Ie, If, Ik, 11 are transistors. (
3e), (3''), diodes (3k), and (3e), respectively, and here, the inductance of the reactor (2) is sufficiently large, and the output current Iw is almost direct current and the positive polarity. It is assumed that it is sexual.

In this case, the waveforms of the PWM signals Pe and Pf will be symmetrical if the voltage correction signal ΔV is zero, but the voltage command value Vw"
Since the positive voltage correction signal Δ■ corresponding to 25% of the peak value of the carrier wave is superimposed on (=0.), the signal becomes asymmetrical, and the pulse width of one PWM signal Pe becomes longer.

However, the output current I- flows through the transistor (3e) as Ie while the transistor (3e) is on, and as I& through the diode (31) while the transistor (3e) is off. flows to

In addition, since the polarity of the output current ll11 is positive, the transistor (
3f) and diode (3kNm C, [and no current flows like Ik).

Therefore, the DC voltage Ed obtained by averaging the output voltage V- is controlled to zero according to the voltage command value Vw', and the voltage non-control period Td
The voltage error caused by is eliminated. This is true even if the voltage command value Vw'' is a value other than zero, and the same is true for the U phase and V phase, which is limited to the W phase.

[Problem M to be solved by the invention] As described above, the conventional PWM converter device sets the voltage command value Vu'' according to the polarity of the output currents Iu, Iv, and Iw.
, Vv'' and Vw'', the voltage correction signal Δ■ is added, so if the output currents Iu, Iv and ■- contain ripple components, the polarity of the output current that fluctuates around zero can be accurately determined. Therefore, the voltage correction signal Δ■ becomes a disturbance, and the harmonics superimposed on the output voltage increase, resulting in a decrease in the power factor and deterioration of the control characteristics of the DC voltage Ed.

This invention was made to solve the above-mentioned problems, and provides a PWM converter device that accurately determines the polarity of the output current, eliminates distortion of the output voltage, and improves DC voltage control characteristics. With the goal.

[Means for Solving the Problems] The PWM converter device according to the present invention has an output current that is ineffective. ! ! A phase difference calculation circuit that calculates the phase difference between the output current and the AC power supply based on the current and effective current, and a current of the output current based on the AC power supply by adding the calculated phase difference to the voltage phase of the AC power supply. It is equipped with an adder that outputs the phase, and a phase comparator that is provided within the PWM signal generation circuit and that determines the polarity of the output current based on the current phase.

[Operation] In this invention, a voltage correction signal is added to the voltage command value based on the polarity of the output current determined from the current phase,
This eliminates polarity discrimination errors due to ripple components included in the output current, reduces harmonics included in the output voltage, and improves the power factor and DC voltage control characteristics.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. 1st
The figure is a block diagram showing one embodiment of the present invention, and the components indicated by symbols (1) to (21) and (23) to (29) are the same as those described above.

Phase comparator (22A) in PWM signal generation circuit (21)
corresponds to the above-mentioned comparator (22), and is configured to determine the polarity of the output current I based on the current phase from the adder, which will be described later.

The phase difference calculation circuit (30) calculates the phase difference φ of the output current I with respect to the power supply voltage E based on the reactive current Id and the active current Iq from the coordinate converter (9). .

Adders (31> to (33)) add the phase difference φ from the phase difference calculation circuit (30) to the voltage phases θBu, θBv, and 89w of each phase from the phase detector (8), respectively, and calculate the current phase. It outputs θlu, elv and 01m.

Figure 2 shows reactive current Id and active current r of DC amount, respectively.
q, output current I, invalid voltage setting value ■d*, effective voltage setting value Vq*, voltage command value V*, and power supply voltage E. The difference vector ωLI of V8 is the reactor (2)
ω is the angular frequency of the AC power supply (1) and the inductance of the axle (2). Also, the output current ■ is a composite vector of the active current rq and the reactive current Id, and the voltage command value V8 is the effective voltage setting value vq1
1 and the reactive voltage setting value Vd'', the effective 71+'', jib:, I +: and the effective voltage setting value ■q11 are the in-phase components of the power supply voltage E, the reactive current 1d and the reactive voltage setting value Vd'' are This is the orthogonal component of the power supply voltage E.

Next, referring to FIG. 2, the operation of the embodiment of the present invention shown in FIG. 1 will be described.

As is clear from FIG. 2, the phase difference φ between the output current I with respect to the power supply voltage E is the difference between the active current IQ, which is the in-phase component of the power supply voltage E, and the reactive current I, which is the orthogonal component of the power supply voltage E.
d, φ= jan−' (I d/I q) −
It is represented by ■. Therefore, the phase difference calculation circuit (30) is
The computation of equation 0 is performed on the reactive current Id and active current IQ input from the coordinate converter (9), and the phase difference φ of the output current I with respect to the power supply voltage E is output.

This phase difference φ is added to the voltage phases θBu, θBv, and 01m by adders (31) to (33), respectively, to obtain the current phases θ[u, θIV, and θ■− of the output current ■,
The signals are input to phase comparators (22^) in the PWM signal generation circuits (19) to (21) for each phase.

For example, the phase comparator (22^) in the W-phase PWM signal generation circuit (21) is configured such that the current phase θ■- is 2nπ≦θ1w
< (2n+ 1)π-■ or (2n+1)π≦θtw< (2n+ 2)π...
(2) However, it is determined whether n: satisfies an integer. If the formula ■ is satisfied, the polarity of the output current ■ is determined to be positive and a positive output signal is input to the regulator (23), and if the formula 0 is satisfied, the polarity of the output current I is determined to be positive. is determined to be negative and inputs a negative output signal to the regulator (23).

The regulator (23) outputs a voltage correction signal Δ■ with a polarity corresponding to the polarity of the output current ■ and a magnitude corresponding to the voltage-time product of the voltage non-control period Td, and outputs the voltage correction signal Δ■ with a polarity corresponding to the polarity of the output current ■. Add to voltage command value ■1. This operation is performed similarly for the other phases, and PWM signals Pa to Pf are generated and applied to the power converter (3) in the same manner as described above.

In this way, the phase difference calculation circuit (30) and the adder (31)
Using ~(33), the current phases θlu, θ■V and θ■-
By determining the polarity of the output current ■, it is possible to add the voltage correction signal Δ■ with a polarity that accurately corresponds to the polarity of the output current ■ to the voltage command value Vw'', and the DC voltage Ed can be controlled with high precision.6 [Invention [Effect] As described above, according to the present invention, there is provided a phase difference calculation circuit that calculates the phase difference between the output current and the AC power source based on the reactive current and active current of the output current, and the phase difference calculation circuit that calculates the phase difference between the output current and the AC power source based on the reactive current and active current of the output current. and a phase comparator to determine the polarity of the output current based on the current phase, and output the output determined from the current phase. Since the voltage correction signal is added to the voltage command value based on the polarity of the current, polarity discrimination errors due to ripple components included in the output current are eliminated, harmonics included in the output voltage are reduced, and the power factor and This has the effect of providing a PWM converter device with improved DC voltage control characteristics.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a vector diagram for explaining the phase difference of output currents, and FIG.
The figure is a block diagram showing a conventional PWM converter device, and FIGS. 4 and 5 are waveform diagrams for explaining the operation of the conventional PWM converter device. (1)... AC power supply (3)... Power converter (3a) to (3f)... Transistor (switching element) (8)... Phase detector (9)... Coordinate converter (19) to (21)...PWM signal generation circuit (
22^)...Phase comparator (23)...Adjuster (
27)... Comparator (28), (29)...
・Delay element (30)...Phase difference calculation circuit (31)~
(33)... Adder Vu", Vv", Vw" - Voltage command value I u, I v, I va - Output current Id... Reactive current rq... Effective current φ... Phase difference θBu , θBv, θB-... Voltage phase θlu, θd,
θl--Current phase Δ■...Voltage correction signal Vc...Carrier wave Q, i:
J...On signal Pa-Pf...PWM signal In the signal diagram, the same reference numerals indicate the same or corresponding parts. secretion 2 diagram

Claims (1)

[Claims] A power converter including a switching element, and a PWM for controlling the switching element to turn on according to a voltage command value.
A PWM converter device that has a PWM signal generation circuit that outputs a signal and converts AC power from an AC power source into DC power via the power converter, comprising: a phase detector that detects a voltage phase of the AC power source; , a coordinate converter that calculates a reactive current and an active current of the output current based on the AC power supply based on the output current and the voltage phase of the power converter, and a coordinate converter that calculates the reactive current and active current of the output current based on the reactive current and active current, a phase difference calculation circuit that calculates a phase difference between a current and the AC power source; and an adder that adds the phase difference to the voltage phase and outputs a current phase of the output current with the AC power source as a reference. , the PWM signal generation circuit includes: a phase comparator that determines the polarity of the output current based on the current phase; and a voltage correction signal that outputs a voltage correction signal for correcting the voltage command value according to the polarity of the output current. a regulator; a comparator that compares the corrected voltage command value with a carrier wave and outputs an on signal; and delays the rise timing of the on signal by a time proportional to the voltage correction signal to generate the PWM signal. A PWM converter device comprising: a delay element that outputs an output;