JPH06284737A - Control method of link parallel resonance-type power converter - Google Patents

Abstract

PURPOSE:To reduce the ripple of an output current in a converter part. CONSTITUTION:In the control method of a DC link parallel resonance-type power converter, at least one resonance phenomenon period is provided between the zero-voltage period of a resonant capacitor 3 constituting the DC link parallel resonance-type power converter and a resonance phenomenon period in which the switching pattern of an inverter part 4 decided within the zero-voltage period is output actually. During the zero-voltage period, the control amount of the part of the converter at the start of a zero-voltage period of next time is found by an estimation operation device 10 by using a switching pattern, of next time, which is output during a resonance phenomenon period immediately after the finish of the zero-voltage period. The estimated value of the control amount is compared with a control-amount instruction value by a comparator 1, switching-pattern data is obtained, and, on the basis of it, the switching pattern of a resonance phenomenon period of two times later is decided by a shift register 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a DC link parallel resonance type power converter, and more particularly, it relates to a zero voltage period for determining a switching pattern of a converter section and a resonance phenomenon period based on the switching pattern. The present invention relates to a control method in which at least one resonance phenomenon period is provided between them.

[0002]

2. Description of the Related Art FIG. 5 shows a main circuit configuration of a DC link parallel resonance type inverter. In the figure, 1 is a DC power supply (voltage value E _d ), 2 is a resonance reactor (inductance value L _r ), 3 is a resonance capacitor (capacitance value C _r ), and 4 is a switching element consisting of a transistor and a diode, which is a three-phase bridge. It is an inverter unit as a connected converter unit. As is well known, the characteristic of this converter is that a period (zero voltage period) in which the voltage of the resonance capacitor 3 is zero [V] is forcibly created by utilizing the resonance phenomenon of the LC resonance circuit, and during this period. In principle, the switching loss is zero by switching the inverter unit 4.

Here, the current flowing through the resonance reactor 2 is i _Lr , the input current of the inverter unit 4 is i _INV , and the voltage across the resonance capacitor 3 is v _link . In the main circuit of the DC link parallel resonance type inverter of FIG. 5, in which only two of the resonance reactor 2 and the resonance capacitor 3 are added to the DC link part of the inverter device, i _INV is changed by changing the switching pattern of the inverter part 4. If it decreases,
v _link becomes an abnormally high voltage, and the resonance reactor 2
A large current flows through.

FIG. 6 is a diagram showing the waveforms of v _link , i _INV and i _Lr when this phenomenon occurs. That is, when i _INV is reduced at t _{n + 1} immediately after the start of the zero voltage period of the resonance capacitor 3 created by utilizing the resonance phenomenon of the resonance reactor 2 and the resonance capacitor 3, as shown in FIG. A high voltage is generated in the resonance phenomenon period T _{n + 1} , and the current i _Lr flowing through the resonance reactor 2 increases to the negative side.

As a control method for suppressing the above-mentioned high voltage and large current of the DC link part, Japanese Patent Application No. 4-28 of the same applicant can be used.
There is a control method according to No. 6834. This control method
This will be described with reference to FIG. According to this control method, at the start time t _n of the zero voltage period, a switching pattern is output during the resonance phenomenon period T _n after the end of the zero voltage period and during the next resonance phenomenon period T _{n + 1.} By setting the initial current of the resonance reactor 2 at the resonance phenomenon period start time t _{n + 1} in consideration of the two switching patterns of the resonance phenomenon period, the abnormality of v _link occurring in the resonance phenomenon period T _{n + 1.} It suppresses the increase in voltage and the increase in reactor current.

The switching pattern of the inverter unit 4 corresponds to logic "1" and "0" for turning on the transistors of the upper arm and the lower arm, for example U, V,
The switching pattern is (1, 1, 1) when the upper arm transistor of each W phase is turned on, and the switching pattern is (0, 0, when the lower arm transistor is turned on.
0). There are eight switching patterns in total, and the output voltage vector (instantaneous space voltage vector) of the inverter unit 4 in each case is shown in FIG.

[0007]

In the above prior art, it is now assumed that the control amount for the inverter unit 4 is the output voltage integrated value (magnetic flux). FIG. 7 shows, as an example, the waveforms of the U-phase magnetic flux detection value and the magnetic flux command value. The solid line in the figure indicates the magnetic flux detection value when the control is delayed by one resonance phenomenon period, and the broken line indicates the magnetic flux detection when the control is not delayed. The value and the one-dot chain line show the magnetic flux command value, respectively.

The problems of the prior art will be described below with reference to FIG. As described above, in the above conventional technique, at the start time t _n of the zero voltage period, not only the switching pattern of the resonance phenomenon period T _n after the end of the zero voltage period but also the next resonance phenomenon period T _{n + 1} The switching pattern must be known in advance. Therefore, in this control method, the switching pattern output during the resonance phenomenon period T _{n + 1} at the start t _n of the zero voltage period is determined. That is, regarding the resonance period T _n , the switching pattern output at that time is t _n−1 at the start of the zero voltage period.
Is determined by comparing the detected magnetic flux value with the magnetic flux command value, and thus the magnetic flux control is delayed by one resonance phenomenon period.

As shown in FIG. 7, the waveform of the solid line when the control is delayed has a larger amplitude of the magnetic flux detection value than the waveform of the broken line when the control is not delayed. That is, a delay in control causes an increase in ripple, and this increase in magnetic flux ripple causes an increase in output current ripple. Inverter part 4
Even when the control amount for the output current and the output voltage other than the magnetic flux is set, there is a problem that the ripple of the output current increases due to the above reason.

The present invention has been made to solve the above problems, and an object of the present invention is to improve the method for determining a switching pattern to reduce the ripple of the output current and to reduce the ripple of the output current. It is to provide a control method of a power converter.

[0011]

In order to achieve the above object, a first invention uses a switching pattern which is output during a resonance phenomenon period immediately after the end of the zero voltage period in the zero voltage period of the resonance capacitor. Then, the control amount of the converter unit at the start of the next zero voltage period is predicted, and the control amount predicted value is compared with the control amount command value to determine the switching pattern.

A second invention is the same as the first invention,
The controlled variable is the magnetic flux that is obtained by integrating the output voltage of the converter, and the output voltage at the start of the next zero voltage period is determined by using the switching pattern that is output during the resonance phenomenon period immediately after the zero voltage period during the zero voltage period. The magnetic flux as the integrated value is predicted, and the switching pattern is determined by comparing the predicted magnetic flux value and the magnetic flux command value.

A third invention is the same as the first invention,
The control amount as the output current of the converter unit, in the zero voltage period, predict the output current at the start of the next zero voltage period using the switching pattern output during the resonance phenomenon period immediately after the end of the zero voltage period, The switching pattern is determined by comparing the current predicted value and the current command value.

A fourth invention is the same as the first invention,
The control amount is the output voltage of the converter unit, and in the zero voltage period, the output voltage at the start of the next zero voltage period is predicted by using the switching pattern output during the resonance phenomenon period immediately after the end of the zero voltage period, The switching pattern is determined by comparing the predicted voltage value and the voltage command value.

[0015]

According to the present invention, the zero voltage period at the start t _n of the resonant capacitor, only the next (1 resonance period using a switching pattern output to the resonance period T _n immediately after completion of the zero-voltage period earlier ) Predict the control amount (magnetic flux or output current or output voltage) at the start of the zero voltage period t _{n + 1} , compare this with the control amount command value, and output in the next resonance phenomenon period T _{n + 1.} Determine the switching pattern.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit configuration diagram showing an embodiment of the first invention. The same components as those in FIG. 5 are designated by the same reference numerals and detailed description thereof will be omitted. Hereinafter, different parts will be mainly described.

In FIG. 1, 6 is a current detector for detecting the current i _Lr of the resonance reactor 2, 7 is a zero voltage detector for detecting that the voltage v _link of the resonance capacitor 3 is zero, and 8 is an inverter. Magnetic flux provided on the output side of the section 4,
A control amount detector for detecting a control amount such as an output current and an output voltage, a current detector 9 for detecting an output current of the inverter unit 4, and a control amount prediction 10 for predicting a control amount at the start of the next zero voltage period. An arithmetic unit, 11 is a comparator that compares the control amount predicted value and the control amount command value, and 12 is a comparator 11
And a shift register which receives the output signal of the zero voltage detector 7 as an input and outputs a switching pattern in the next and next resonance phenomenon periods, and 13 receives the output signals of the shift register 12 and the current detector 9 as an input, and starts the resonance phenomenon period. Initial current command value calculator for calculating the initial current command value of the resonance reactor 2 of FIG.
It is a drive pulse generation circuit that receives the output signals of the initial current command value calculator 13 and the current detector 6 as input, matches the switching pattern with the initial current command value, and generates a drive pulse for the inverter unit 4. Further, 5 indicates a motor as a load.

Next, the operation of this embodiment will be described along with the data flow in FIG. First, when the zero voltage detector 7 detects the start of control (zero voltage), the prediction calculator 10
By the control amount detected by the control amount detector 8,
Based on the switching pattern output from the shift register 12 in the next resonance phenomenon period, the predicted control amount value at the start of the next zero voltage period is calculated. The control amount predicted value and the control amount command value are compared by the comparator 11 to determine the switching pattern data.

The switching pattern data is latched by the shift register 12 to generate a switching pattern which is output during the next resonance phenomenon period. The initial current command value calculator 13 calculates an initial current command value for the reactor based on the next and next two switching patterns from the shift register 12 and the output current detection value from the current detector 9. This initial current command value and the next switching pattern are the drive pulse generation circuit 1
4, the drive pulse of the inverter unit 4 is generated, and the inverter unit 4 is controlled.

In this embodiment, at the beginning of the zero voltage period,
Using the switching pattern output in the resonance phenomenon period after the end of the zero voltage period, the control amount prediction calculator 10 predicts the control amount at the start of the next (one resonance phenomenon period ahead) zero voltage period, and The switching pattern output during the next resonance phenomenon period is determined by comparison with the control amount command value. Therefore, the influence of the control delay of the control amount during one resonance phenomenon period as described in the prior art is canceled out, and the ripple of the control amount can be reduced and the ripple of the output current can be reduced.

FIG. 2 shows an embodiment of the second invention, which has substantially the same configuration as that of the embodiment of FIG. 1 except that the control amount is a voltage integral value (magnetic flux). In this example,
The control amount detector serves as a magnetic flux detector 8A including an integrator 8a that integrates the output phase voltage of the inverter unit 4. In the predictive computing unit 10a, based on the magnetic flux φ _{U, V, W} obtained by the magnetic flux detector 8A and the switching pattern output in the next resonance phenomenon period, the next zero voltage period start time t shown in Table 1 is calculated. _The predicted magnetic flux value for each phase at _{n + 1} is calculated.

Here, as described above, the upper arm of each phase,
Logic "1" and "0" for turning on the lower arm transistors
Switching function that associates the _{(S U, S V, S} W) introduced, when expressed by the voltage vectors as shown in FIG. 8, the magnetic flux predicted value is as shown in Table 1. In Table 1, K ₁ is a constant determined by the magnetic flux detection filter constant, the resonance period, the power supply voltage and other circuit constants.

[0023]

[Table 1]

The magnetic flux prediction value and the magnetic flux command value obtained by the mathematical formulas in Table 1 are compared by the comparator 11 to determine the switching pattern output during the next resonance phenomenon period via the shift register 12, and in FIG. The inverter unit 4 is controlled according to the data flow described. According to this embodiment, in order to predict the magnetic flux value at the start of the zero voltage period, which is one resonance phenomenon period ahead, and compare it with the magnetic flux command value to determine the switching pattern output in the next resonance phenomenon period. The influence of the magnetic flux control delay during one resonance phenomenon period is canceled out, and the magnetic flux ripple and thus the output current ripple can be reduced.

FIG. 3 shows an embodiment of the third invention.
In this embodiment, since the control amount is the output current of the inverter unit 4, the current detector 9 in FIG. 1 is used as the control amount detector to obtain the current detection value. In the prediction calculator 10b, based on the current i _{U, V, W} obtained by the current detector 9 and the switching pattern output in the next resonance phenomenon period, the next zero voltage period start time t shown in Table 2 is calculated. Calculate the predicted current value for each phase at _{n + 1} . In Table 2, K ₂ is a constant determined by the resonance period, the current detector gain and other circuit constants.

[0026]

[Table 2]

The predicted current value and the current command value obtained by the mathematical formulas in Table 2 are compared by the comparator 11 to determine the switching pattern output during the next resonance phenomenon period through the shift register 12, and in FIG. The inverter unit 4 is controlled according to the data flow described. According to this embodiment, the output current value at the start of the zero voltage period, which is one resonance phenomenon period ahead, is predicted, and this is compared with the current command value to determine the switching pattern output in the next resonance phenomenon period. Therefore, the influence of the control delay of the current during one resonance phenomenon period is canceled out, and the output current ripple can be reduced.

FIG. 4 shows an embodiment of the fourth invention.
In this embodiment, since the controlled variable is the output voltage of the inverter unit 4, the controlled variable detector is a voltage detector 8C constituted by a low-pass filter 8c that removes the high frequency component of the phase voltage and extracts only the fundamental wave. Is. In the prediction calculator 10c, the phase voltages v _{U, V, W} obtained by the voltage detector 8C,
Based on the switching pattern output in the next resonance phenomenon period, the predicted voltage value for each phase at the start time t _{n + 1} of the next zero voltage period shown in Table 3 is calculated. In Table 3, K ₃ is a constant determined by the voltage detection filter constant, the resonance period and other circuit constants.

[0029]

[Table 3]

The predicted voltage value and the voltage command value obtained by the mathematical formulas in Table 3 are compared by the comparator 11 to determine the switching pattern to be output during the next resonance phenomenon period via the shift register 12, and in FIG. The inverter unit 4 is controlled according to the data flow described. According to this embodiment, the output voltage value at the start of the zero voltage period, which is one resonance phenomenon period ahead, is predicted, and this is compared with the voltage command value to determine the switching pattern output in the next resonance phenomenon period. Therefore, the influence of the control delay of the voltage during one resonance phenomenon period is canceled out, and the output current ripple can be reduced.

The present invention can be applied not only to the DC link parallel resonance type inverter but also to the DC link parallel resonance type converter.

[0032]

As described above, according to the present invention, at the start of the zero voltage period of the resonance capacitor, the switching pattern output during the resonance phenomenon period after the end of the zero voltage period is used for the next time (one resonance phenomenon period). To predict the control amount (magnetic flux or output current or output voltage) at the start of the zero voltage period, and compare this with the control amount command value to determine the switching pattern output during the next resonance phenomenon period. The influence of the control delay in the one resonance phenomenon period in the related art is canceled out, and the ripple of the control amount can be reduced to reduce the ripple of the output current.

Although the present invention is characterized by the method of determining the switching pattern, it has the effect of suppressing the high voltage and the large current during the resonance phenomenon period when used in combination with the conventional technique.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram showing an embodiment of a first invention.

FIG. 2 is a circuit configuration diagram showing an embodiment of a second invention.

FIG. 3 is a circuit configuration diagram showing an embodiment of a third invention.

FIG. 4 is a circuit configuration diagram showing an embodiment of a fourth invention.

FIG. 5 is a main circuit configuration diagram of a DC link parallel resonance type inverter.

6 is a voltage and current waveform diagram of each part in FIG.

FIG. 7 is an explanatory diagram of a U-phase magnetic flux detection value and a magnetic flux command value.

FIG. 8 is an output voltage vector diagram of the inverter.

[Explanation of symbols]

 1 DC power supply 2 Resonance reactor 3 Resonance capacitor 4 Inverter unit 5 Motor 6, 9 Current detector 7 Zero voltage detector 8 Control amount detector 8A Magnetic flux detector 8C Voltage detector 8a Integrator 8c Low-pass filter 10, 10a, 10b, 10c Prediction calculator 11 Comparator 12 Shift register 13 Initial current command value calculator 14 Drive pulse generation circuit

Claims (4)

[Claims] 1. A zero voltage period of a resonance capacitor that constitutes a DC link parallel resonance type power converter, and a resonance phenomenon period during which a switching pattern of the converter section determined within this zero voltage period is actually output. In the meantime, in the control method of the DC link parallel resonance type power converter having at least one or more resonance phenomenon periods, the switching pattern output during the resonance phenomenon period immediately after the end of the zero voltage period is used in the zero voltage period. DC link parallel resonance type power conversion characterized by predicting the control amount of the converter unit at the start of the next zero voltage period and comparing the control amount predicted value with the control amount command value to determine the switching pattern. Control method. 2. The method for controlling a DC link parallel resonance type power converter according to claim 1, wherein the controlled variable is a magnetic flux obtained by integrating the output voltage of the converter unit, and the control amount is set in a zero voltage period immediately after the end of the zero voltage period. The switching pattern output during the resonance phenomenon period is used to predict the magnetic flux as the output voltage integrated value at the start of the next zero voltage period, and the switching pattern is determined by comparing this predicted magnetic flux value with the magnetic flux command value. A method for controlling a DC link parallel resonance type power converter characterized by the above. 3. The method of controlling a DC link parallel resonance type power converter according to claim 1, wherein a controlled variable is an output current of the converter unit, and during a zero voltage period during a resonance phenomenon period immediately after the end of the zero voltage period. DC link parallel resonance characterized by predicting the output current at the start of the next zero voltage period by using the switching pattern output to the controller and comparing the predicted current value with the current command value to determine the switching pattern. Type power converter control method. 4. The method of controlling a DC link parallel resonance type power converter according to claim 1, wherein the controlled variable is an output voltage of the converter unit, and during the resonance phenomenon period immediately after the end of the zero voltage period during the zero voltage period. DC link parallel resonance characterized by predicting the output voltage at the start of the next zero voltage period by using the switching pattern output to the output and comparing the predicted voltage value with the voltage command value to determine the switching pattern. Type power converter control method.