JP3488861B2 - DC power supply - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC power supply device, and more particularly to a DC power supply device that rectifies an AC voltage to output a desired DC voltage, improves a power factor of the AC voltage, and reduces a harmonic current. .

[0002]

2. Description of the Related Art A conventional AC-DC converter has a step-up chopper circuit composed of an AC power source, a rectifying element, a reactor, a switching element, a reverse current blocking diode, and a smoothing capacitor, and is a ratio of ON time of the switching element. The power factor is improved by controlling the duty signal so that the input current has a sinusoidal waveform synchronized with the power supply voltage.
Further, the DC voltage is controlled by changing the amplitude of the sine waveform according to the DC voltage value and the DC voltage command value. As such a DC power source, for example, JP-A-1
No. 0-327576.

[0003]

In the conventional DC power supply device, since the DC voltage is controlled by changing the amplitude of the sine waveform, the amplitude of the input current becomes large due to torque control and large load fluctuations. There is a problem that the control is not stable when there is a change.

Therefore, the main object of the present invention is to provide a method in which the amplitude of the input current changes greatly due to torque control or large load changes, even if there are differences in the power supplies used or changes in the power supply voltage. An object of the present invention is to provide a DC power supply device capable of stably improving the power factor and reducing the harmonic current.

[0005]

The present invention detects the input current and detects the balance of the waveform of the detected input current, thereby adjusting the waveform balance and improving the power factor. The system can be stabilized against a change in state such as a load change.

Further, by detecting the balance of the input current waveform by the ratio or difference of the integrated values in the first half and the latter half of the input power supply half-wave cycle, an appropriate phase correction amount can be obtained according to the degree of balance, Control response becomes good.

Further, when obtaining the balance of the input current waveform, the larger of the integrated values of the first half and the latter half of the input power supply half-wave cycle is used as the denominator to obtain the ratio, whereby the waveform balance is biased to the first half and the latter half. Adjustment can be performed with the same amount of phase correction as when biased to, and control is stable.

Further, when the integrated value of the latter half of the input power source half-wave cycle is larger than the integrated value of the first half, it is possible to perform an appropriate phase correction by determining that the waveform balance is biased to the latter half. become.

Further, when the integrated value in the latter half of the input power supply half-wave cycle is smaller than the integrated value in the first half, it is possible to perform appropriate phase correction by determining that the waveform balance is biased to the first half. Becomes

Further, when the current waveform balance is biased toward the latter half of the input power supply half-wave cycle, the current waveform balance can be corrected by outputting the phase correction amount that delays the phase of the sine wave data. It can improve the rate and stabilize the system.

Further, when the current waveform balance is biased to the first half in the half cycle of the input power supply, the current waveform balance can be corrected by outputting the phase correction amount that advances the phase of the sine wave data. It can improve the power factor and stabilize the system.

Further, by providing the upper limit value for the phase correction amount corrected by the current waveform balance, the phase correction amount becomes too large, the PWM duty becomes small near the zero cross timing of the power supply voltage, and the power factor decreases. Can be prevented.

Further, by obtaining the sine wave data with reference to the zero-cross timing of the power supply voltage, it becomes possible to control the current waveform in a sine wave shape synchronized with the power supply voltage.

Furthermore, by creating phase data corrected by the current waveform balance with reference to the zero-cross timing of the power source voltage, it is possible to control the current waveform in a balanced sine wave shape synchronized with the power source voltage. Wave data can be obtained.

Further, by controlling the current waveform in a balanced sine wave shape synchronized with the power supply voltage, the input power factor can be controlled to approximately 1 while maintaining the waveform balance of the input current.

Further, by obtaining the peak value of the input current, it becomes possible to estimate the target current instantaneous value from the value.

Furthermore, by sequentially obtaining the target current instantaneous value at which the input power factor becomes 1, the PWM duty correction for adjusting the input current waveform so that the input power factor becomes approximately 1 can be performed.

Further, by controlling the current peak value to a low value and successively obtaining the target current instantaneous value, the PWM duty for adjusting the input current waveform so that the input power factor becomes approximately 1 while suppressing the peak current to a low level. Corrections can be made.

Further, by controlling the maximum on-time of the PWM duty to control the output DC voltage,
Even if the input power is small, the output DC voltage can be controlled to be equal to the DC voltage command value.

Furthermore, by controlling the output DC voltage by controlling the amplitude of the sine wave data, the output DC voltage can be controlled to be equal to the DC voltage command value even when the input current is large.

Furthermore, since the amplitude of the sine wave data is maximum when the maximum on-time of the PWM duty is controlled, the output DC voltage can be controlled stably when the input power is small.

Furthermore, when the amplitude of the sine wave data is controlled, the maximum on-time of the PWM duty is the maximum, so the output DC voltage can be controlled stably when the input power is large. You can

Further, by providing an upper limit value for the DC voltage command value, it is possible to prevent the output DC voltage from becoming too large and destroying the constituent elements of the boost converter section due to the breakdown voltage overshoot.

Further, the PWM reference duty becomes maximum near the zero cross timing of the power supply voltage and becomes minimum at the phase θ = π / 2, and changes in a sine wave shape in synchronization with the power supply voltage, and the phase changes depending on the balance of the current waveform. By correcting, the power factor can be stably improved even if there is a difference in the used power supply or a change in the power supply voltage.

Further, by controlling the DC output voltage with the maximum on-time of the PWM duty and the amplitude of the sine wave data without depending on the input current waveform, the amplitude of the input current fluctuates greatly due to torque control or large load fluctuations. Even in such a case, the DC output voltage can be stably controlled.

Further, by obtaining the PWM duty adjustment value from the difference between the target current instantaneous value and the input current instantaneous value, it is possible to perform fine adjustment so that the input current waveform matches the target current waveform.

Further, by setting the added value of the PWM reference duty and the PWM duty adjustment value as the PWM duty, the input current waveform becomes a sine wave in synchronism with the power supply voltage, and there are differences in the power supplies used and fluctuations in the power supply voltage. However, the power factor can be controlled to almost 1.

[0028]

1 is a block diagram showing the overall configuration of a DC power supply device according to an embodiment of the present invention. Figure 1
In, the AC power supply 1, the rectifying element 2, the reactor 3, the diode 4, the switching element 5, and the smoothing capacitor 6
A boost converter unit is constituted by and. The AC voltage from the AC power supply 1 is given to the bridge-connected rectifying element 2 via the reactor 3 and rectified. A switching element 5 is connected to the output side of the rectifying element 2 via a current detecting means 9. Switching element 5 is on,
The off operation controls the accumulation and release of energy with respect to the reactor 3. The diode 4 prevents the reverse flow of current. The smoothing capacitor 6 smoothes the rectified pulsating flow into a DC voltage, and the voltage across the smoothing capacitor 6 is supplied to the load 7.

Zero-cross detection means 8 is connected to both ends of the AC power supply 1. The zero-cross detection means 8 detects the zero-cross timing of the power supply voltage, and the detection signal is given to the converter control device 10. Also,
The current detecting means 9 detects the input current and gives the detection signal to the converter control device 10.

The converter control unit 10 is the phase calculation means 1
1, a sine wave generator 12, a waveform balance detector 13, a current amplitude detector 14, a multiplier 15, a DC voltage controller 16, a current controller 17, and a PWM signal generator 18. Then, the converter control device 10 outputs three input signals of the zero-cross signal of the detection output of the zero-cross detection means 8, the input current of the detection output of the current detection means 9 and the DC output voltage as the voltage across the smoothing capacitor 6. A PWM signal for controlling the switching element 5 is output so that the input current has a sine wave waveform synchronized with the power supply voltage and the DC output voltage is equal to the DC voltage command value.

More specifically, the waveform balance detecting means 13 detects the balance of the current waveform detected by the current detecting means 9, and the detected signal is detected by the phase calculating means 1
Give to one. The phase calculation means 11 corrects the reference phase of the sine wave data at the zero-cross timing according to the phase correction amount α output from the waveform balance detection means 13, and gives the correction signal to the sine wave generation means 12. The sine wave generation means 12 generates sine wave data corresponding to the phase data obtained by the phase calculation means 11. Current amplitude detection means 1
Reference numeral 4 detects the amplitude of the input current waveform based on the detection output of the current detection means 9, and supplies the detection output to the multiplier 15.

The multiplier 15 multiplies the current amplitude value detected by the current amplitude detecting means 14 and the sine wave data generated by the sine wave generating means 12 to obtain a target current instantaneous value and gives it to the current control means 17. . The DC voltage control means 16 controls the maximum on-time of the PWM duty and the amplitude of the sine wave data so that the output DC voltage across the smoothing capacitor 6 matches the voltage command value. The current control means 17 determines the instantaneous current value from the current detection means 9, the target instantaneous current value from the multiplier 15, the sine wave data from the sine wave generation means 12, and the maximum on-time of the PWM duty from the DC voltage control means 16. The PWM duty is generated based on
Give to. The PWM signal generation means 18 is the current control means 17
A PWM pulse signal to be applied to the switching element 5 is created and output based on the PWM duty from.

FIG. 2 is a diagram showing a current waveform depending on the phase state of the sine wave data. When the PWM duty for controlling the switching element 5 shown in FIG. 1 is changed in a sine wave shape synchronized with the power supply voltage, if the phases of the sine waves are out of phase, the current waveform is out of balance and the power factor is reduced. Figure 2 (a)
2B is a state in which the phase of the sine wave is advanced with respect to the power supply voltage, FIG. 2B is a state in which the phase of the sine wave is delayed with respect to the power supply voltage, and FIG. 2C is in phase. That is the case.

FIG. 3 is a flow chart for explaining the operation of the waveform balance detecting means shown in FIG. 1, and FIG. 4 is a diagram showing sampling timing.

It is assumed that the current value I detected by the current detecting means 9 is sampled, for example, 10 times within a power source half-wave cycle of 0 to π. The integrated value A in the first half (0 to π / 2 period) of the power supply half-wave cycle is A in step SP1 shown in FIG.
= Σ (I0, I4), and the integrated value B of the latter half of the power supply half-wave cycle (period of π / 2 to π) is calculated as B = Σ (I5, I9) in step SP2. In step SP3, the magnitudes of A and B are compared, and if A> B, it is determined that the waveform balance is biased toward the first half, and in step SP4, the ratio calculation is performed with A as the denominator, and the formula (1) is calculated. The phase correction amount α is obtained by

Phase correction amount α = H × B / A−H (1) If A <B, it is determined that the waveform balance is biased toward the latter half, and in step SP6 a ratio calculation is performed with B as the denominator. The phase correction amount α is calculated by the equation (2).

Phase correction amount α = H × A / B−H (2) H is a constant for converting the ratio of integrated values into an appropriate phase correction amount.

The phase correction amount α obtained by the equations (1) and (2) is always a negative value. If A> B, the correction for advancing the phase is made, so the absolute value of the phase correction amount α according to the equation (1) is made the final phase correction amount α in step SP5. If A <B, correction is performed to delay the phase, so the phase correction amount α according to the equation (2) is used as it is as the final phase correction amount α. If the phase correction amount α becomes too large, P near the zero cross timing of the power supply voltage
Since the WM duty becomes small and the current waveform is distorted from the sine wave shape, an upper limit value is provided so that the phase correction amount α does not exceed the upper limit value.

The phase calculating means 11 sequentially finds a reference phase θ'which changes from 0 to π from the zero cross timing of the power supply voltage obtained from the zero cross detecting means 8 to the next zero cross timing. Furthermore, this reference phase θ ′
And the phase correction amount α obtained from the waveform balance detection means 13
Is added and the final phase data θ is output. This is shown in Equation (3).

Final phase data θ = reference phase θ ′ + phase correction amount α (3) The sine wave generation means 12 generates sine wave data corresponding to the phase data θ obtained from the phase calculation means 11. By these operations, the sine wave data synchronized with the power supply voltage is sequentially created.

FIG. 5 is a block diagram showing the internal structure of the current control means 17 shown in FIG. The current control means 17 is
From the sine wave data obtained from the sine wave generating means 12, the maximum ON time K1 of the PWM duty obtained from the DC voltage control means 16 and the amplitude K2 of the sine wave data, the PWM reference duty D1 is calculated by the formula shown in the equation (4). Sequentially ask.

PWM reference duty D1 = K1 × (1−K2 × Sinθ) (4) K1 and K2 are decimal numbers of 1.0 or less, and initial values are K1 = 0 and K2 = 1.0, respectively.

As is clear from the equation (4), the PWM reference duty D1 becomes maximum near the zero cross timing of the power supply voltage, becomes minimum at the phase θ = π / 2, and changes in a sine wave shape in synchronization with the power supply voltage. . Further, as the maximum ON time K1 of the PWM duty increases, the change width of the PWM reference duty D1 within the power supply half-wave cycle increases, and as the amplitude K2 of the sine wave data decreases, the phase θ increases.
The PWM reference duty D1 at = π / 2 becomes large.

The DC voltage control means 16 receives the output DC voltage Vdc detected from the smoothing capacitor 6 and the DC voltage command value Vdc * so that the output DC voltage Vdc becomes equal to the DC voltage command value Vdc *. , The maximum ON time K1 of the PWM duty and the amplitude K2 of the sine wave data 2
Controls one parameter.

FIG. 6 shows DC in the DC voltage control means 16.
It is a flow chart which shows the control procedure of voltage. In step SP11 of FIG. 6, it is determined that the output DC voltage Vdc is smaller than the DC voltage command value Vdc *, and in step SP12 the maximum PWM duty ON time K1.
If it is determined that is not the maximum, step SP
At 13, the maximum ON time K1 of the PWM duty is increased. In step SP12, it is determined that the maximum PWM duty ON time K1 is the maximum, and in step SP
When it is determined that the amplitude K2 is not the minimum in 14,
In step SP15, the amplitude K2 of the sine wave data is reduced. However, in step SP14, the amplitude K of the sine wave data
If 2 is the minimum, nothing is done and control exits.

Output DC voltage V in step SP11
It is determined that dc is larger than the DC voltage command value Vdc *, and the amplitude K2 of the sine wave data is determined in step SP16.
If it is determined that is not the maximum, step SP
At 17, the amplitude K2 of the sine wave data is increased. When it is determined in step SP16 that the amplitude K2 of the sine wave data is the maximum, and when it is determined in step S18 that the maximum ON time K1 of the PWM duty is not the minimum,
In step SP19, the maximum on-time K1 is reduced. However, if it is determined in step SP18 that the maximum ON time K1 of the PWM duty is the minimum,
Exit control without doing anything.

As is apparent from the above DC voltage control procedure, when the DC voltage control means 16 controls the maximum ON time K1 of the PWM duty, the amplitude K2 of the sine wave data is maximum, and When controlling the amplitude K2 of the wave data, the maximum ON time K1 of the PWM duty
Is the largest.

FIG. 7 is a waveform diagram showing how the PWM duty changes during DC voltage control. FIG. 7A shows the PWM duty.
FIG. 7 shows a case of controlling the maximum on-time of the duty.
(B) shows a case where the amplitude of the sine wave data is controlled. 7A and 7B, when the DC voltage is increased, the direction changes from (1) to (2), and when the DC voltage is decreased, the direction changes from (2) to (1). . The DC voltage command value Vdc * has an allowable upper limit value, and D
The C voltage control means 16 controls the output DC voltage Vdc so as not to exceed the upper limit value.

The current amplitude detecting means 14 detects the maximum value of the current value for each half-wave cycle of the power source and outputs it as the current amplitude data Ip. The current amplitude data Ip is the sine wave generating means 12
Is multiplied by the sine wave data sequentially generated by, and the target current instantaneous value I * is obtained. Therefore, the target current instantaneous value I * is sequentially obtained by the equation (5).

Target current instantaneous value I * = current amplitude data Ip × Sinθ (5) Further, the target current instantaneous value I * may be obtained by multiplying the current amplitude data Ip by a decimal value of 1.0 or less. Good. In this case, the control is performed so that the peak value of the current waveform is kept low. When the decimal value for suppressing the peak value is represented by S, the target current instantaneous value I * is sequentially obtained by the equation (6).

Instantaneous target current value I * = S × current amplitude data Ip × Sinθ (6) The current control means 17 detects the instantaneous current value I * of the target current obtained by the equation (5) or the equation (6). According to the difference from the input current instantaneous value I obtained from the means 9, the PWM duty adjustment value D2 is obtained from the equation (7) described later, and the PWM reference duty D1 obtained by the equation (4) is corrected.

If the detected input current instantaneous value I is smaller than the target current instantaneous value I *, the duty is increased, and if the detected input current instantaneous value I is larger than the target current instantaneous value I *. Correct the duty so that it decreases. In order to reflect the difference between the target current instantaneous value I * and the input current instantaneous value I in proportion to the PWM reference duty D1, the PWM duty adjustment value D2 is sequentially obtained by the equation (7). .

PWM duty adjustment value D2 = C × (I * −I) × D1 (7) Here, C is a constant, and is used to determine the ratio of the adjustment value D2 reflected in the finally obtained PWM duty. It is a thing.

The final PWM duty D is (8)
As shown in the formula, it is sequentially obtained by the sum of the PWM reference duty D1 and the PWM duty adjustment value D2.

PWM duty D = PWM reference duty D1 + PWM duty adjustment value D2 (8) According to the above procedure, the PWM duty D obtained by the current control means 17 is output to the PWM signal generating means 18 and the PWM pulse signal. Is created and the switching element 5 is driven.

The converter control device 10 is operated by the above-mentioned procedure.
By driving the switching element 5 with the PWM pulse signal created by, the input power factor can be controlled to approximately 1 while maintaining the waveform balance of the input current.
It is possible to control the DC output voltage so as to match the command value.

The embodiments disclosed this time are to be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description but by the claims, and is intended to include meanings equivalent to the claims and all modifications within the scope.

[0058]

As described above, according to the present invention, by detecting the balance of the input current waveform, it is possible to adjust the waveform balance to improve the power factor, and to reduce the state change such as load fluctuation. On the other hand, the system can be stabilized.

[Brief description of drawings]

FIG. 1 is a block diagram showing an overall configuration of a DC power supply device according to an embodiment of the present invention.

FIG. 2 is a waveform diagram showing a current waveform depending on the phase state of sine wave data.

FIG. 3 is a flowchart for explaining the operation of the waveform balance detection means.

FIG. 4 is a diagram showing a current sampling timing of the waveform balance detection means.

FIG. 5 is a block diagram showing an internal configuration of a current control unit.

FIG. 6 is a flowchart for explaining the operation of the DC voltage control means.

FIG. 7 is a waveform diagram showing how the PWM duty changes during DC voltage control.

[Explanation of symbols]

1 AC power supply, 2 rectifier circuit, 3 reactor, 4 diode, 5 switching element, 6 smoothing capacitor, 7 load, 8 zero cross detection means, 9 current detection means, 10 converter control device, 11 phase calculation means,
12 sine wave generating means, 13 waveform balance detecting means,
14 current amplitude detecting means, 15 multiplier, 16 DC voltage controlling means, 17 current controlling means, 18 PWM signal generating means.

Claims (11)

(57) [Claims] 1. A rectifier circuit for converting an AC voltage of an input power source into a DC voltage, a reactor connected to an input side or an output side of the rectifier circuit, and energy storage and release with respect to the reactor by intermittent control. a switching element, in the direct-current power supply and a smoothing capacitor provided on the output side of the switching element, a current detecting means for detecting an input current wave Katachiba the detected input current by said current detecting means < br /> The lance is detected and the phase correction amount is calculated based on the detection result.
And wave balance detecting means for outputting a target based on the phase and the phase correction amount of the AC voltage
Target current generating means for generating an instantaneous current value, and the output DC voltage is equal to the DC voltage command value, and
The instantaneous value of the input current detected by the current detection means is the target voltage.
P of the switching element so as to be equal to the instantaneous value of the flow.
And a control means for controlling the WM duty . 2. The waveform balance detecting means, wherein the waveform balance of the input current is a half-wave cycle of the input power source.
If there is a bias in the latter half of the
Output the phase correction amount, and the input current waveform balance is the half-wave cycle of the input power supply.
If there is a bias in the first half of the
The DC power supply device according to claim 1, which outputs a phase correction amount to be advanced . 3. The waveform balance detecting means is provided in each of a first half period and a second half period of a half-wave cycle of the input power source .
There seeking integrated value of the input current value, their ratio or difference
Accordingly, it characterized that you detect the wave balance of the input current, the DC power supply device according to claim 1 or claim 2. 4. The waveform balance detection means is configured to input the input current in a first half period and a second half period of a half-wave cycle of the input power source.
Calculate the ratio with the larger of the integrated values as the denominator,
Characterized Rukoto determined the phase correction amount based on the ratio, the DC power supply device according to claim 3. 5. The waveform balance detector is configured to detect the phase.
Characterized Rukoto an upper limit value of the correction amount, the DC power supply device according to claim 4. 6. The target current generating means detects a zero-cross timing of the AC voltage and detects a zero-cross timing.
Zero-crossing detection means for outputting a loss signal, and a reference phase and the above-mentioned complement obtained from the zero-crossing signal
Phase calculation means for calculating phase data based on positive quantity
And a sine that generates sine wave data based on the phase data
Amplitude of the input current detected by the wave generation means and the input current detection means
Current amplitude detection means for detecting the current amplitude data, and the current amplitude data obtained from the current amplitude detection means
Multiply by the sine wave data generated by the sine wave generation means
And outputs the multiplied value as the target current instantaneous value.
Characterized in that it comprises a multiplier, claim from claim 1
5. The DC power supply device according to any one of 5 . 7. The current amplitude data and the sine wave data
Parameter and a decimal value less than 1.0
The DC power supply device according to claim 6 , wherein the DC power supply device is an hour value . 8. The control means controls the output DC voltage
The PWM duty is adjusted so that it becomes equal to the DC voltage command value.
Control the maximum on-time of the
8. The DC power supply device according to claim 6, further comprising a DC voltage control means for controlling the amplitude of the data. 9. The direct current voltage control means comprises the sine wave demultiplexer.
When the amplitude of the data is maximum, the PWM duty
Control the maximum on-time of the
When the maximum on-time is maximum, the sine wave data
9. The DC power supply device according to claim 8, wherein the amplitude of the power supply is controlled . 10. The DC voltage command value has an allowable upper limit value.
9. The claim 8 or claim , characterized in that it is provided.
Item 13. The DC power supply device according to Item 9 . 11. The sine wave generated by the sine wave generating means is further controlled by the control means.
Data and the positive voltage controlled by the DC voltage control means.
By the amplitude value of the chord wave data and the DC voltage control means
Multiplied value with the maximum on-time of the controlled PWM duty
PW controlled by the DC voltage control means
Subtract the multiplication value from the maximum ON time of M duty
PWM reference that outputs the value as the PWM reference duty
Detected by the duty calculator, the target current instantaneous value and the input current detection means.
PWM duty according to the difference from the output instantaneous value of input current
A PWM duty adjustment value calculation unit for obtaining an adjustment value, the PWM reference duty and the PWM duty adjustment
The value added with the value is output as the PWM duty.
Characterized in that it comprises a calculation unit, wherein claims 8 to claim 1
0. The DC power supply device according to 0.