JP3635844B2 - converter - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a converter that converts DC input power so as to be compatible with a connected load or distribution system and supplies the converted load to a load.
[0002]
[Prior art]
An example of a conventionally used converter will be described with reference to FIG. The converter 1 is constituted by a DC power source 2, a non-resonant type inverter unit comprising an inverter circuit 4 and a high-frequency transformer 5, a rectifier bridge 6, a coil 7, a frequency conversion circuit 8 and a control circuit 9. The inverter circuit 4 converts the direct current of the direct current power source 2 into a high frequency of several tens of kHz by four transistors 4a, 4b, 4c, and 4d. The output of the inverter circuit 4 is rectified and smoothed by the rectifier bridge 6 and the coil 7 connected to the secondary side of the high-frequency transformer 5, and the frequency conversion circuit 8 is driven at 60 Hz by the control circuit 9. Yes.
[0003]
[Problems to be solved by the invention]
However, in the conventional converter, the inverter circuit 4 and the frequency conversion circuit 8 are each composed of four switching elements, and the number of parts is large, and the switching element itself needs to be of a high withstand voltage / high current type. There is a problem that it is difficult to realize small size, light weight and low price.
[0004]
[Means for Solving the Problems]
In the present invention, the inverter unit is a resonance type, and the converter has a simple configuration and can be stably controlled.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
According to the first aspect of the present invention, the switching element connected to the primary winding of the high frequency transformer and the resonance capacitor connected to both ends of the primary winding of the high frequency transformer or between the collector and emitter of the switching element The generated inverter output is transmitted to the high frequency transformer, and the output current is determined by controlling the frequency conversion circuit connected to the secondary winding of the high frequency transformer based on the waveform information of the output voltage or output current. The control means controls the resonance drive means to turn on the switching element at a timing when the collector-emitter voltage of the switching element is 0 or near zero, and outputs the current and The resonance condition of the switching element is controlled so that the waveform becomes a predetermined value .
[0006]
According to the second aspect of the present invention, the control means determines the ON time of the switching element so as to be proportional to the difference between the voltage signal detected by the voltage detection means and the current signal detected by the current detection means, and is stable. It is a converter that can be controlled.
[0007]
According to a third aspect of the present invention, the control means determines the ON time of the switching element so as to be proportional to an integral value of a predetermined time of the voltage signal detected by the voltage detection means and the current signal detected by the current detection means. Thus, the converter that can solve the influence of the steady deviation and can stabilize the waveform of the output current can be controlled stably.
[0008]
According to a fourth aspect of the present invention, the control means determines the ON time of the switching element according to the differential value of the difference between the voltage signal detected by the voltage detection means and the current signal detected by the current detection means, and responds. The converter has good characteristics and can perform stable control.
[0009]
According to the fifth aspect of the present invention, the control means determines the proportionality constant based on the voltage obtained from the voltage detection means so that the output current can be controlled more finely and a converter that can obtain a stable output waveform is provided. .
[0010]
According to the sixth aspect of the present invention, the control means determines the integration constant based on the voltage obtained from the voltage detection means, has no influence of the steady-state deviation, can control the output current more finely, and has a stable output waveform. It is a converter that can obtain
[0011]
According to the seventh aspect of the present invention, the control means determines the differential constant based on the voltage obtained from the voltage detection means, so that the response is high, the output current can be controlled more finely, and a stable output waveform is obtained. It is a converter that can.
[0012]
In the invention described in claim 8, the control means can determine the proportionality constant based on the phase of the voltage obtained from the voltage detection means, and can finely control the output current without being directly affected by the fluctuation of the voltage waveform. The converter can obtain a stable output waveform.
[0013]
According to the ninth aspect of the present invention, the control means determines the integration constant based on the phase of the voltage obtained from the voltage detection means, so that the control means is not directly affected by the fluctuation of the voltage waveform and is not affected by the steady deviation. In this converter, the output current can be finely controlled and a stable output waveform can be obtained.
[0014]
In the invention described in claim 10, the control means determines the differential constant based on the phase of the voltage obtained from the voltage detection means, and is not directly affected by fluctuations in the voltage waveform, has high responsiveness, and has an output current. The converter is capable of finely controlling the output and obtaining a stable output waveform.
[0015]
【Example】
Example 1
The first embodiment of the present invention will be described below. FIG. 1 is a block diagram showing the configuration of this embodiment. Reference numeral 11 denotes a converter according to the present embodiment, which converts the output of the DC power source 2 such as a solar battery and supplies a commercial frequency sine wave AC power to the load 3. The converter 11 includes a high-frequency transformer 16, a resonant capacitor 14 connected to both ends of the primary winding of the high-frequency transformer 16, a switching element 12 formed of an IGBT, and a diode 17 a connected to the secondary winding of the high-frequency transformer 16. A rectifier 17 composed of a capacitor 17b, a waveform smoothing coil 18, a frequency converter 19 for converting the output of the rectifier 17 into a predetermined frequency, and a current transformer for detecting the waveform of the output current of the frequency converter 19 Current detecting means 22 constituted by, etc., voltage detecting means 23 constituted by a transformer or the like for detecting the waveform of the output voltage of the frequency conversion circuit 19, resonance drive means 20 for resonance driving the switching element 12, and frequency conversion circuit 19 Frequency conversion circuit drive means 21 for driving the current detection means 22 or voltage detection circuit 22 Waveform of the current frequency conversion circuit 19 receives the information of the unit 23 outputs are a control unit 24 for controlling the resonant drive means 20 and the frequency converter drive unit 21 so as to have a predetermined waveform. A reverse conducting diode 13 is connected between the collector and emitter of the switching element 12. The frequency conversion circuit 19 includes four transistors 19 a, 19 b, 19 c, and 19 d and operates according to instructions from the frequency conversion drive means 21. That is, the transistor 19a / transistor 19d and the transistor 19b / transistor 19c are paired and are sequentially turned on. The resonance drive unit 20 performs PWM control of the switching element 12 in the resonance oscillation region, and the control unit 24 sets the resonance condition of the switching element 12 so that the output and waveform of the current detected by the current detection unit 22 have a predetermined value. In order to control, it is comprised with a microcomputer, DSP, IC, discrete components, etc.
[0016]
The operation of this embodiment will be described below. When a switch (not shown) is turned on and the output of the DC power supply 2 is connected to the converter 11, the converter 11 starts operation. The high-frequency voltage switched by the switching element 12 is supplied to the primary winding of the high-frequency transformer 16, and this high-frequency voltage is converted into a predetermined magnitude and output to the secondary winding of the high-frequency transformer 16. This secondary voltage is rectified by the rectifying means 17, the waveform is smoothed by the waveform smoothing coil 18, and converted to the commercial frequency by the frequency conversion circuit 19. The load 3 is supplied with AC power of this commercial frequency.
[0017]
At this time, in this embodiment, the primary coil of the switching element 12, the resonant capacitor 14, and the high-frequency transformer 16 is a resonance type inverter unit, so the configuration is very simple compared to the conventional one. .
[0018]
The resonance operation of the present embodiment will be described below with reference to FIGS. 2, VGE is the gate voltage of the switching element 12, VCE is the collector-emitter voltage, VP is the voltage waveform of the primary winding of the high-frequency transformer 16, IP is the same current waveform, and IL is the coil 18 The current waveform is shown. When the switching element 12 is turned on during the on period TON based on the instruction from the resonance drive means 20, a linearly increasing current IP flows through the primary winding of the high-frequency transformer 16. At this time, VP is the output voltage E of the DC power supply 2. Further, when the switching element 12 is turned off in the off period TOFF according to an instruction from the resonant drive means 20, the inductance of the primary winding of the high-frequency transformer 16 and the resonant capacitor 14 form a resonant circuit. Therefore, during this period, VP · IP has a high frequency resonance waveform. That is, assuming that the inductance of the primary winding at resonance is L1 and the capacitance of the resonance capacitor 14 at resonance is C, the energy L1IP2 / 2 stored in the primary winding during the TON period is CVP2 / The energy stored in the resonant capacitor 14 is converted into the primary winding of the high-frequency transformer 16. Thus, a high-frequency current IP flows through the primary coil of the high-frequency transformer 16, and a high-frequency voltage similar to this waveform is generated. Therefore, a high frequency voltage similar to the voltage generated in the primary coil is generated in the secondary coil of the high frequency transformer 16. By changing the TON time, the amount of IP current and the peak voltage value of VCE can be changed. The above oscillation operation will be described in a macro manner with reference to FIG. The control means 24 controls the TON time so that the current waveform obtained from the current detection means 22 matches the voltage waveform obtained from the voltage detection means 23. At this time, the envelope of the VCE has a sine waveform in which the negative side of the commercial frequency is inverted as shown in FIG. 3 by controlling the TON time. A voltage similar to this VCE is generated in the secondary side coil of the high-frequency transformer 16, and a current shown as IP2 in FIG. By rectifying the current IP2 by the rectifying means 17, the waveform current IL having only the envelope portion of the current IP2 flows in the waveform smoothing coil 18. This current IL is frequency-converted by a frequency conversion circuit 19 driven by an instruction from the frequency conversion circuit drive means 21. That is, the transistors 19a and 19d or the transistors 19b and 19c are driven alternately. Therefore, the current IL is divided into a current Ia and a current Ib shown in FIG. 3, and the output current IO which is a sine wave of commercial frequency is supplied to the load 3 by reversing the positive and negative.
[0019]
Here, the control means 24 controls the resonance drive means 20 to turn on the switching element 12 at a timing when VCE is 0 or near 0. For this reason, the level of generated electromagnetic noise is extremely low, and the switching loss generated in the switching element 12 is very small.
[0020]
As described above, in this embodiment, the primary winding of the high-frequency transformer 16, the resonant capacitor 14, and the switching element 12 function as a resonant inverter, and the secondary winding of the high-frequency transformer 16, the rectifier 17 and the waveform smoothing unit. The converter supplies power to the load 3 via the coil 18 and the frequency conversion circuit 19. In this way, a converter with a low level of generated electromagnetic noise is realized with a simple configuration in which only one switching element 12 is used in the inverter unit.
[0021]
(Example 2)
Next, a second embodiment of the present invention will be described. FIG. 4 is a block diagram showing the configuration of this embodiment. In this embodiment, the control means 24 uses the voltage waveform at both ends of the load 3 detected by the voltage detection means 23 as the reference waveform r and the waveform of the output current detected by the current detection means 22 as y. In other words, control is performed so that the r and y waveforms match each other, that is, the deviation e between r and y is set to zero. For this reason, the manipulated variable u for the resonant drive means 20 is determined using a control law as shown in equation (1).
[0022]
u = Kp · e (Kp: proportionality constant) (Equation 1)
Equation 1 indicates that the manipulated variable u is proportional to the deviation e. That is, in this embodiment, the ON time of the switching element 12 is determined so as to be proportional to the difference between the voltage signal detected by the voltage detection means 23 and the current signal detected by the current detection means 22.
[0023]
For this reason, according to this embodiment, a converter capable of stabilizing the waveform of the output current can be realized.
[0024]
(Example 3)
Next, a third embodiment of the present invention will be described. FIG. 5 is a block diagram showing the configuration of this embodiment. In this embodiment, the control means 24 uses the voltage waveform at both ends of the load 3 detected by the voltage detection means 23 as the reference waveform r and the waveform of the output current detected by the current detection means 22 as y. In other words, control is performed so that the r and y waveforms match each other, that is, the deviation e between r and y is set to zero. For this reason, the manipulated variable u for the resonant drive means 20 is determined using a control law as shown in Equation 2.
[0025]
u = Ki · ∫edt (Ki: integral constant) (Equation 2)
That is, in this embodiment, the control unit 24 sets the ON time of the switching element so as to be proportional to an integral value of a predetermined time between the voltage signal r detected by the voltage detection unit 23 and the current signal y detected by the current detection unit 22. It is what we are going to decide. For this reason, according to the present embodiment, it is possible to solve the problem that the steady-state deviation that is a problem in the second embodiment remains, and to realize a converter that can stabilize the waveform of the output current.
[0026]
Example 4
Next, a fourth embodiment of the present invention will be described. FIG. 6 is a block diagram showing the configuration of this embodiment. In this embodiment, the control means 24 determines the operation amount according to the differential value of the difference between the voltage signal detected by the voltage detection means 23 and the current signal detected by the current detection means 22. That is, the operation amount u for the resonant drive means 20 is determined using the control law shown in Equation 3.
[0027]
u = Kd · de / dt (Kd: differential constant) (Equation 3)
For this reason, according to the present embodiment, the increase / decrease trend of the deviation can be reflected in the determination of the operation amount, the problem that the response characteristic which is a problem in the third embodiment is poor can be solved, and the waveform of the output current can be stabilized. It can realize a converter that can.
[0028]
(Example 5)
Next, a fifth embodiment of the present invention will be described. FIG. 7 is a block diagram showing the configuration of this embodiment. In the present embodiment, the control unit 24 determines the proportionality constant Kp described in the second embodiment based on the voltage obtained from the voltage detection unit 23. That is, Kp is determined according to the flowchart described in FIG.
[0029]
First, in step 1, the current signal r detected by the current detection means 22 is received, and in step 2, it is determined whether or not the value r is equal to or greater than the predetermined value Va shown in FIG. If the result is YES, the process proceeds to step 3 where the manipulated variable u is determined as equation (4). If the result is No, the process proceeds to step 4 where the manipulated variable u is determined to be equation 5.
[0030]
u = KpHi · e (KpHi: proportional constant) (Equation 4)
u = KpLow · e (KpLow: proportional constant) (Equation 5)
As described above, according to the present embodiment, the value of the proportionality constant Kp is properly used for two types of KpHi and KpLow according to the magnitude of the current signal r. Therefore, it is possible to realize a converter that can control the output current more finely and obtain a stable output waveform.
[0031]
In this embodiment, the proportionality constant Kp is divided into two types, KpHi and KpLow, but it can be easily divided into three or more types as required.
[0032]
Further, the concept of the flowchart shown in FIG. 8 can be applied to the third embodiment. The operation amount u at this time is as shown in Equations 6 and 7.
[0033]
u = KiHi · ∫edt (KiHi: proportional constant) (Equation 6)
u = KiLow · ∫edt (KiLow: proportional constant) (Expression 7)
Naturally, even in this control, it is possible to realize a converter capable of finely controlling the output current and obtaining a stable output waveform.
[0034]
Similarly, the idea of the flowchart shown in FIG. 8 can be applied to the fourth embodiment. The operation amount u at this time is as shown in Equations 8 and 9.
[0035]
u = KdHi · de / dt (KdHi: differential constant) (Equation 8)
u = KdLow · de / dt (KdLow: differential constant) (Equation 9)
(Example 6)
Next, a sixth embodiment of the present invention will be described. FIG. 10 is a block diagram showing the configuration of the control means used in this embodiment. In the present embodiment, the control means 24 has a phase detection means 26 and a waveform control means 27. The phase detector 26 detects the phase T of the voltage signal r detected by the voltage detector 23. The waveform control means 27 has an operation program shown in the flowchart of FIG.
[0036]
Hereinafter, the operation of the waveform control means 33 will be described. In step 1, the phase detection means 32 receives the phase information T detected from the voltage obtained from the voltage detection means 23, and in step 2, it is checked whether or not the phase information T is within a predetermined range. That is, it is checked whether Ta ≦ T ≦ Tb. The Ta · Tb is classified according to the phase angle from the zero-cross point of the AC voltage as shown in FIG. In this embodiment, 0 ≦ Ta <π / 6, π / 6 ≦ Tb <5 / 6π, and 5 / 6π ≦ Ta, but it is not necessary to limit to this. If the result of this check is YES, in step 3, the proportionality constant Kp is determined as KpHi. If the result of the check is No, the proportional constant Kp is determined to be KpLow in step 4. Accordingly, the manipulated variable u in each case is as shown in the above equations 3 and 4.
[0037]
Thus, if the proportionality constant Kp is determined by the phase angle from the zero cross point, the problem of the fifth embodiment can be solved. That is, in the fifth embodiment, the proportional constant Kp is determined by using the predetermined voltage Va as a reference voltage and by raising and lowering the reference voltage. Therefore, stable control cannot be performed when the output voltage fluctuates sharply due to the influence of noise or the like. In this respect, according to the present embodiment, the proportionality constant Kp is determined by the phase angle from the zero cross point, so that it is not directly affected by the fluctuation of the voltage waveform.
[0038]
Also, the operation program shown in FIG. 10 can be applied to the third and fourth embodiments. The manipulated variable u at this time is as shown in Equation 6, Equation 7, Equation 8, and Equation 9.
[0039]
【The invention's effect】
The invention described in claim 1 includes a high-frequency transformer, a switching element connected to a primary winding of the high-frequency transformer, a resonant capacitor connected in parallel to the primary winding of the high-frequency transformer, and a secondary winding of the high-frequency transformer. A rectifier connected to the frequency converter, a frequency converter for converting the output of the rectifier to a predetermined frequency, a current detector for detecting a waveform of an output current of the frequency converter, and a waveform of an output voltage of the frequency converter. The frequency conversion circuit receives information from the voltage detection means, the resonance drive means for resonantly driving the switching element, the frequency conversion circuit drive means for driving the frequency conversion circuit, and the current detection means or the voltage detection means and outputs the frequency conversion circuit. the waveform of the current is closed and control means for controlling the resonant drive means and frequency converting circuit drive means so as to have a predetermined waveform, said system The means controls the resonant drive means to turn on the switching element at a timing when the collector-emitter voltage of the switching element is 0 or near zero, and the current output and waveform become a predetermined value. As a configuration for controlling the resonance condition of the switching element , the inverter unit is a resonance type, and a converter having a simple configuration and capable of stable control is realized.
[0040]
In the invention described in claim 2, the control means determines the on-time of the switching element so as to be proportional to the difference between the voltage signal detected by the voltage detection means and the current signal detected by the current detection means, A converter capable of stable control is realized.
[0041]
According to a third aspect of the present invention, the control means determines the ON time of the switching element so as to be proportional to an integral value of a predetermined time between the voltage signal detected by the voltage detection means and the current signal detected by the current detection means. In this way, the converter capable of solving the influence of the steady deviation and stabilizing the waveform of the output current can be realized.
[0042]
According to a fourth aspect of the present invention, the control means determines the ON time of the switching element according to a differential value of a difference between the voltage signal detected by the voltage detection means and the current signal detected by the current detection means. This realizes a converter with good responsiveness and stable control.
[0043]
According to the fifth aspect of the present invention, the control means realizes a converter that can control the output current more finely and obtain a stable output waveform as a configuration in which the proportional constant is determined by the voltage obtained from the voltage detection means. Is.
[0044]
In the invention described in claim 6, the control means determines the integration constant based on the voltage obtained from the voltage detection means, has no influence by the steady-state deviation, can control the output current more finely, and has a stable output waveform. The converter which can be obtained is implement | achieved.
[0045]
According to the seventh aspect of the present invention, the control means is configured to determine the differential constant based on the voltage obtained from the voltage detection means, so that the response is high and the output current can be controlled more finely and a stable output waveform can be obtained. It is to realize a converter that can.
[0046]
The invention described in claim 8 is a configuration in which the control means determines the proportionality constant based on the phase of the voltage obtained from the voltage detection means, and can finely control the output current without being directly affected by fluctuations in the voltage waveform. This realizes a converter that can obtain a stable output waveform.
[0047]
The invention described in claim 9 is a configuration in which the control means determines the integration constant based on the phase of the voltage obtained from the voltage detection means, and is not directly affected by the fluctuation of the voltage waveform, and is not affected by the steady deviation, It is intended to realize a converter capable of finely controlling the output current and obtaining a stable output waveform.
[0048]
According to a tenth aspect of the present invention, the control means is configured to determine the proportionality constant based on the phase of the voltage obtained from the voltage detection means. It is a converter that can be finely controlled and can obtain a stable output waveform.
[Brief description of the drawings]
FIG. 1 is a block diagram showing the configuration of a converter according to a first embodiment of the present invention. FIG. 2 is a waveform diagram showing the operation of each part. FIG. 3 is a waveform diagram showing the operation of each part. FIG. 5 is a block diagram showing a configuration of a converter according to a second embodiment of the present invention. FIG. 5 is a block diagram showing a configuration of a converter according to a third embodiment of the present invention. FIG. 7 is a block diagram illustrating a converter according to a fifth embodiment of the present invention. FIG. 8 is a flowchart illustrating a control program included in the control means. FIG. 10 is a waveform diagram of an output voltage for explaining a reference value Va. FIG. 10 is a block diagram showing a configuration of control means included in a converter according to a sixth embodiment of the present invention. Flow chart showing the control program Preparative [12] the waveform diagram for explaining the phase angle 13 is a block diagram illustrating a converter which is a conventional example [Description of symbols]
12 switching element 14 resonant capacitor 16 high frequency transformer 17 rectifying means 19 frequency converting circuit 20 resonant driving means 21 frequency converting circuit driving means 22 current detecting means 23 voltage detecting means 24 control means 26 phase detecting means 27 waveform shaping means

Claims (10)

A high-frequency transformer, a switching element connected to the primary winding of the high-frequency transformer, a resonant capacitor connected in parallel to the primary winding of the high-frequency transformer, a rectifying means connected to the secondary winding of the high-frequency transformer, and a rectifying means A frequency conversion circuit for converting the output of the output into a predetermined frequency, current detection means for detecting the waveform of the output current of the frequency conversion circuit, voltage detection means for detecting the waveform of the output voltage of the frequency conversion circuit, and the switching element Resonance drive means for resonance driving, frequency conversion circuit drive means for driving the frequency conversion circuit, and a current waveform output from the frequency conversion circuit upon receiving information from the current detection means or voltage detection means is a predetermined waveform. have a control means for controlling the resonant drive means and frequency converting circuit drive means as said control means, said resonant drive The switching element is controlled so that the switching element is turned on at a timing when the collector-emitter voltage of the switching element is 0 or in the vicinity of 0, and the output condition and waveform of the current have a predetermined value. To control the converter.   2. The converter according to claim 1, wherein the control means determines the on-time of the switching element so as to be proportional to a difference between the voltage signal detected by the voltage detection means and the current signal detected by the current detection means.   2. The converter according to claim 1, wherein the control means determines the on-time of the switching element so as to be proportional to an integral value of a predetermined time between the voltage signal detected by the voltage detection means and the current signal detected by the current detection means.   2. The converter according to claim 1, wherein the control unit determines the on-time of the switching element in accordance with a differential value of a difference between the voltage signal detected by the voltage detection unit and the current signal detected by the current detection unit.   3. The converter according to claim 2, wherein the control means determines the proportionality constant based on the voltage obtained from the voltage detection means.   4. The converter according to claim 3, wherein the control means determines the integration constant based on the voltage obtained from the voltage detection means.   5. The converter according to claim 4, wherein the control means determines the differential constant based on the voltage obtained from the voltage detection means.   3. The converter according to claim 2, wherein the control means determines the proportionality constant based on the phase of the voltage obtained from the voltage detection means.   4. The converter according to claim 3, wherein the control means determines the integration constant based on the phase of the voltage obtained from the voltage detection means.   5. The converter according to claim 4, wherein the control means determines the differential constant based on the phase of the voltage obtained from the voltage detection means.

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