JP4410429B2 - Single phase bridge inverter - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a single-phase bridge inverter using a controllable electric valve such as a transistor, MOSFET, IGBT, thyristor, gate turn-off thyristor (GTO).
[0002]
[Prior art]
A single-phase PWM inverter of single pulse PWM is combined with a converter, a transformer, etc. as necessary, so that a high-frequency intermediate link dc / dc in a photovoltaic power generation inverter system, a fuel cell inverter system, a vehicle auxiliary power supply, etc. It is used in various applications such as converters, inverters for high-frequency welding machines, inverters for high-frequency heating, and unit inverters for three-phase large-capacity multiple inverters used in reactive power control devices.
[0003]
FIG. 12 is a single-phase bridge inverter configured by the first to fourth controllable electric valves Q1, Q2, Q3, and Q4 that performs power conversion between DC power and single-phase AC power. The anodes of the control electric valves Q1 and Q3 are connected to the positive terminal P of the DC power supply Ed, the cathodes of the controllable electric valves Q2 and Q4 are connected to the negative terminal N of the DC power supply Ed, and the cathode of the controllable electric valve Q1 Is connected to the anode of the controllable electric valve Q2, the connection point is the AC output terminal U1, the cathode of the controllable electric valve Q3 is connected to the anode of the controllable electric valve Q4, and the connection point is connected to the AC output terminal U2. To do.
Further, feedback diodes D1, D2, D3, D4 are connected in reverse parallel to the controllable electric valves Q1, Q2, Q3, Q4, respectively.
[0004]
Next, the control operation, particularly the switching operation of each controllable electric valve will be described. Now, among the controllable electric valves Q1, Q2, Q3, Q4, the state where Q1 and Q4 are turned on is S1, the state where Q1 and Q3 are turned on, S2, and the state where Q2 and Q3 are turned on , S3, and the state of turning on Q2 and Q4 as S4, switching is performed in the order of S1 → S2 → S3 → S4 → S1... Or S1 → S4 → S3 → as shown in FIG. Any modulation method of switching in the order of S2 → S1... Is adopted. For convenience, the former is referred to as a normal rotation mode, and the latter is referred to as a reverse rotation mode.
[0005]
A switching operation of S1 → S2 → S3 → S4 → S1 in the forward rotation mode and S1 → S4 → S3 → S2 → S1 in the reverse rotation mode corresponds to one cycle of the AC output voltage VL. Furthermore, S1 that generates a positive voltage and S3 that generates a negative voltage appear alternately every half cycle, but the AC output voltage VL is controlled by changing the electrical angle α of the duration.
[0006]
FIG. 14 shows current waveforms flowing through the controllable electric valves Q1 to Q4 and the feedback diodes D1 to D4 when the modulation method is the forward rotation mode and the load is a resistance R and a reactor L connected in series. FIG. In the figure, the darkly filled portions indicate the currents of the controllable electric valves Q1 to Q4, and the lightly filled portions indicate the currents of the feedback diodes D1 to D4. A rectangular wave indicated by a solid line indicates the AC output voltage VL.
As can be seen from FIG. 14, the controllable electric valves Q1 and Q2 have a greater current burden than Q3 and Q4. In contrast, the feedback diodes D1 and D2 have a smaller current burden than D3 and D4.
[0007]
Of course, since each controllable electric valve and feedback diode having the same rating are used, as a result of the above, the temperature rise of the controllable electric valves Q1 and Q2 is higher than that of Q3 and Q4, and the feedback The temperature rise of the diodes D3 and D4 is higher than that of D1 and D2.
Note that the unbalance of the current load changes depending on the control angle α, and the unbalance disappears when α reaches a maximum of 180 °. However, in an inverter applied to various actual applications, it is required to output a constant AC voltage by absorbing voltage fluctuations of a DC power source, for example, a storage battery or a solar battery. In many cases, there are circuit elements that cause a voltage drop corresponding to the load current, such as a transformer, rectifier, or filter, between the load and the final load. To keep the output voltage (load voltage) constant, It is also required to compensate for the voltage drop. Therefore, this control angle α usually varies in a wide range of 60 ° <α <180 °, and the current imbalance is unavoidable.
[0008]
The above is the case where the main component of the loss of the controllable electric valve is the conduction loss in the operation in the low frequency range. However, in the device operating in the high frequency range, the switching loss is dominant and the switching loss is the conduction loss. May reach 2 to 3 times. The switching loss is determined by the current value at the moment of switching. Therefore, in the case of FIG. 14, the controllable electric valves Q3 and Q4 that are turned off a larger current than the controllable electric valves Q1 and Q2 have a higher switching loss. As a result, in the operation in the high frequency region where the switching loss is dominant, the temperature rise of the controllable electric valves Q3 and Q4 is higher than that of Q1 and Q2.
[0009]
FIG. 15 is a diagram showing waveforms of currents flowing through the controllable electric valves Q1 to Q4 and the feedback diodes D1 to D4 when operated in the reverse rotation mode. 14 is different from the case of the normal rotation mode in FIG.
That is, in this reverse rotation mode, the current burden of the controllable electric valves Q3 and Q4 is larger than that of the controllable electric valves Q1 and Q2, and the current burden of the feedback diodes D1 and D2 is larger than that of D3 and D4.
Further, in the high frequency region where the switching loss is dominant, the loss of the controllable electric valves Q1 and Q2 is larger than that of the controllable electric valves Q3 and Q4.
[0010]
[Problems to be solved by the invention]
The conventional single-phase bridge inverter is configured as described above, and since the control operation is performed, whether the modulation method is the forward rotation mode or the reverse rotation mode, and whether the operation is the low frequency range or the high frequency range, Which of the controllable electric valves Q1 to Q4 has a large power loss and which has a small power loss, depending on whether the load power factor is advanced or delayed, or what value the electrical angle α which is the width of the output voltage is? In any case, although the distribution state is different, in some cases, the current burden of a part of the controllable electric valve is larger than that of the rest of the controllable electric valve, and as a result, the temperature rise of the former is higher than that of the latter. Since the maximum output current of the inverter is determined when the junction temperature of the controllable electric valve reaches a limit temperature (for example, 125 ° C.), for example, in the case of the forward rotation mode in the low frequency range, the controllable electric valves Q3, Q4 Even if there is a margin in the temperature on the side, when the temperature on the controllable electric valve Q1, Q2 side reaches the limit, no further output current can flow as an inverter. For this reason, there was a problem that the utilization factor of an inverter fell.
[0011]
The present invention has been made to solve the above-described problems, and the current burden of each controllable electric valve and feedback diode constituting the inverter is equalized, and the temperature rise is equalized. An object is to provide a single-phase bridge inverter that can be expected to improve.
[0012]
[Means for Solving the Problems]
The single-phase bridge inverter according to claim 1 of the present invention includes a first and a third controllable electric valve whose anode is connected to the DC side positive terminal, respectively, and a second whose cathode is connected to the DC side negative terminal, respectively. And a fourth controllable electric valve, the cathode of the first controllable electric valve and the anode of the second controllable electric valve are connected to one of the AC side terminals, and the third controllable electric valve A valve cathode and an anode of the fourth controllable electric valve are connected to the other of the AC side terminals, and a feedback diode is connected in reverse parallel to each of the first to fourth controllable electric valves. In the phase bridge inverter,
Among the above controllable electric valves, the state in which the first and fourth controllable electric valves are turned on is S1, the state in which the first and third controllable electric valves are on is S2, the second and third When the state of turning on the controllable electric valve is set to S3, and the state of turning on the second and fourth controllable electric valves is set to S4,
The first mode that switches in the order of S1, S2, S3, S4, S1,... And the second mode that switches in the order of S1, S4, S3, S2, S1,. It is what I did.
The single-phase bridge inverter according to claim 2 is:
The first mode that switches in the order of S1, S2, S3, S2, S1, and so on, and the second mode that switches in the order of S1, S4, S3, S4, S1,. It is what I did.
[0013]
The single-phase bridge inverter according to claim 3 switches the first and second modes every predetermined number of cycles.
[0014]
  The single-phase bridge inverter according to claim 4 is:Detecting the difference between the temperature of one or both of the first and second controllable electric valves and the temperature of either or both of the third and fourth controllable electric valves;
The mode is switched according to the polarity of the temperature difference so that the absolute value of the temperature difference is reduced.
The single-phase bridge inverter according to claim 5 is:Detecting the difference between the temperature of one or both of the first and third controllable electric valves and the temperature of either or both of the second and fourth controllable electric valves;
  The mode is switched according to the polarity of the temperature difference so that the absolute value of the temperature difference is reduced.
[0015]
  Claims6The single-phase bridge inverter includes hysteresis comparison means that inputs a detected temperature difference and performs a history operation using a predetermined positive / negative temperature difference as an operating point, and switches modes based on an output signal of the hysteresis comparison means.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
FIG. 1 explains the basic concept of a control system for a single-phase bridge inverter according to Embodiment 1 of the present invention. Note that the main circuit configuration as a single-phase bridge inverter is not re-recorded because there is no difference from FIG. 12 described in the prior art.
FIG. 1 (a) shows the switching system of each controllable electric valve Q1, Q2, Q3, Q4 mentioned in the prior art. Conventionally, as shown in FIG. 1 (b), S1 → S2 → S3 → S4 → The forward rotation mode as the first mode that switches in the order of S1... And the second mode that switches in the order of S1.fwdarw.S4.fwdarw.S3.fwdarw.S2.fwdarw.S1... As shown in FIG. In the present invention, as shown in FIG. 4D, the switching mode is changed from forward rotation to reverse rotation to forward rotation at every cycle at the time of the arrow as shown in FIG.・ It is switched. As a result, the current burden of each of the controllable electric valves Q1 to Q4 is averaged, and thus the temperature rise is also equalized.
FIG. 4E shows an example in which switching is performed every two cycles. As will be described later, this switching can be performed every arbitrary cycle.
[0017]
Hereinafter, a specific configuration example for realizing the control method according to the first embodiment of the present invention, the basic principle of which has been described with reference to FIG. 2 and 3 are circuit configuration examples for creating switching signals of the controllable electric valves Q1, Q2, Q3, and Q4 (here, for convenience, the switching signals are also denoted by reference numerals Q1 to Q4). Show. FIG. 4 is a timing chart showing signal waveforms at various points in FIGS.
[0018]
The oscillator OSC in FIG. 2 generates a pulse with a constant frequency and triggers the flip-flop F1. The flip-flop F1 outputs a rectangular wave signal F1 having a frequency corresponding to the frequency of a triangular wave SK described later (FIG. 4: F1). The flip-flop F2 is triggered by the falling edge of the signal F1, that is, the rising edge of the inverted signal of the signal F1, and the signal F2 is output (FIG. 4: F2). The signal F2 is a signal for distinguishing whether the output of the inverter is a positive voltage (switching state S1) (when F2 = 1) or a negative voltage (S3) (when F2 = 0).
Further, the pulse signal P1 is generated at the rising edge of the signal F1 (FIG. 4: P1). Further, a pulse signal P2 is created from the signals P1 and F2 by an AND 440 (FIG. 4: P2). Further, a pulse signal P3 is created by AND 441 from the signal P1 and the inverted signal of the signal F2 (FIG. 4: P3). The flip-flop F3 outputs the signal F3 by setting with the signal P2 and resetting with the signal P3 (FIG. 4: F3).
[0019]
The signal F3 is a signal B2 (when F3 = 1) or a signal B4 (when F3 = 0) corresponding to the zero period of the comparator COMP output, that is, the inverter output zero period corresponding to S2 and S4 in the forward rotation mode. It is used to distinguish which one is (FIG. 4: B2, B4).
The triangular wave generator CG receives the signal F1, integrates in the positive direction when the signal F1 is 1, and generates the triangular wave SK by integrating in the negative direction when the signal F1 is 0 (FIG. 4: SK).
[0020]
The comparator COMP compares the signal Vc for controlling the voltage output width of the inverter and the triangular wave SK to obtain the comparator output signal COMP (FIG. 4: Vc, COMP).
When the signal Vc is larger than the triangular wave SK, that is, when the signal COMP is 1, the inverter enters the switching state S1 or S3. Conversely, when the signal Vc is smaller than the triangular wave SK, that is, when the signal COMP is 0, the inverter enters the switching state S2 or S4.
[0021]
Next, the procedure for creating the switching signals Q1, Q2, Q3, Q4 of the controllable electric valves based on the signals F2, F3, COMP obtained in the circuit configuration part of FIG. 2 will be described with reference to FIGS. To do. First, an AND 450 of the signal F2 and COMP is taken and a switching state signal S1 is output (FIG. 4: S1). Further, an AND 452 of the inverted signal of the signal F2 and the signal COMP is taken and a switching state signal S3 is output (FIG. 4: S3). Further, an AND 451 of the signal F3 and the inverted signal of the signal COMP is taken and a signal B2 is outputted, and an AND 453 of both inverted signals of the signals F3 and COMP is taken and a signal B4 is outputted (FIG. 4: B2, B4). As will be described later, the signals B2 and B4 become the switching state signals S2 and S4, respectively, during the forward rotation mode operation, and become the switching state signals S4, S2, respectively, during the reverse rotation mode operation.
[0022]
The flip-flops FR and F4 are responsible for switching the switching mode, which is a feature of the present invention. First, the flip-flop FR is triggered by a rising edge of the signal F2, and a switching mode switching command R having a cycle twice that of the signal F2.^*(Fig. 4: R^*). This double period is for switching the switching mode for each cycle described in FIG. 1D. For example, when the switching period is increased as shown in FIG. The number of flip-flop stages may be increased in accordance with the cycle.
The flip-flop F4 has a command R^*The switching mode switching signal R is output by changing the Boolean value in synchronization with the rise of the switching state signal S1 (FIG. 4: R).
[0023]
When signal R is 1 and its inverted signal is 0, AND 454, 455 and OR 458 output signal B2 as switching state signal S2, and AND 456, 457 and OR 459 output signal B4 as switching state signal S4. (FIG. 4: B2, S2, B4, S4). That is, the forward rotation mode is switched in the order of S1, S2, S3, S4, and S1.
Next, when the signal R is 0 and its inverted signal is 1, the signal B2 is output as the switching state signal S4 by the ANDs 456, 457 and OR459, and the signal B4 is switched by the ANDs 454, 455 and OR458. It is output as S2 (FIG. 4: B2, S4, B4, S2). That is, the reverse rotation mode is switched in the order of S1, S4, S3, S2, and S1.
The switching signals Q1, Q2, Q3, Q4 of each controllable electric valve are obtained from the switching state signals S1, S2, S3, S4 obtained as described above by OR 460, 461, 462, 463.
[0024]
FIG. 5 shows current waveforms flowing through the controllable electric valves Q1 to Q4 and the feedback diodes D1 to D4 when the control operation is performed based on the switching signals Q1, Q2, Q3, and Q4 created as described above. FIG. As can be seen from the figure, the forward rotation mode and the reverse rotation mode are switched every cycle, and accordingly, the average current burden of the controllable electric valves Q1 to Q4 is equalized. Similarly, the current burden is equalized for each of the feedback diodes D1 to D4.
Therefore, the temperature rise of each element is also equalized and the utilization rate is improved, and if the same element is used, it is possible to substantially increase the inverter output as compared with the conventional case, and if the inverter output is the same, An element having a lower rating than before can be used, which improves the economic efficiency.
[0025]
Embodiment 2. FIG.
FIG. 6 explains the basic concept of the control method of the single-phase bridge inverter according to the second embodiment of the present invention. Here, switching is performed in the order of S1, S2, S3, S2, S1,. Control for switching mode A as a first mode not using S, and mode B as a second mode not using S2, which switches in order of S1 → S4 → S3 → S4 → S1. The method is adopted.
[0026]
These mode A and mode B switching modes are not generally used because of their asymmetry. Asymmetry here means that the potential of the load is biased to be positive or negative.
That is, the potential at the midpoint of the DC power supply is set to the reference potential 0, and the virtual neutral point potential of the load, that is, the average value of the potential VU1 of the load terminal U1 and the potential VU2 of U2 with respect to the reference potential 0, Think of / 2. This is the common mode voltage across the load. In mode A, when the output voltage is zero, S2 is always used, so the virtual neutral point potential of the load is biased positively. In mode B, when the output voltage is zero, S4 is always used, so the virtual neutral point potential of the load is negatively biased.
In this way, the bias of the virtual neutral point potential of the load may cause a problem over a long period of time due to erosion due to weak electrolysis depending on the type of the load. .
However, an imbalance in the current burden of each controllable electric valve and feedback diode occurs as in the case of the first embodiment. That is, FIG. 7 shows the current burden of each controllable electric valve Q1 to Q4 and the feedback diodes D1 to D4 when switching in mode A. The controllable electric valves Q2 and Q4 are controlled by the controllable electric valves Q1 and Q3. The current burden is increasing. Similarly, in the feedback diode, D2 and D4 have a larger current burden than D1 and D3. However, the loss of the controllable electric valves Q1 and Q3 is larger than that of the controllable electric valves Q2 and Q4 in the high frequency range.
[0027]
FIG. 8 shows a case where switching is performed in mode B, and a detailed description thereof is omitted, but the state of unbalance of the current burden is in the reverse relationship to that in mode A shown in FIG.
FIG. 9 employs the control method of the second embodiment of the present invention shown in FIG. 6B and switches between mode A and mode B for each cycle. In the case of the first embodiment, FIG. It can be seen that the current share of each controllable electric valve and feedback diode is equalized and the utilization rate is improved, as is the case.
Further, by alternately using the mode A in which the virtual neutral point potential of the load is biased positively and the mode B in which the virtual neutral point potential of the load is negatively biased, the virtual neutral point potential of the load becomes 0 on average. The problem that the load potential is biased as in the conventional case is also solved.
[0028]
Embodiment 3 FIG.
10 and 11 are circuit configuration diagrams showing the switching control system of the single-phase bridge inverter according to the third embodiment of the present invention. In the first and second embodiments, the switching mode in which the current load of the controllable electric valve is different is switched every cycle or every predetermined multiple cycles, thereby equalizing the current load of each controllable electric valve and thereby increasing the temperature. Is equalized. On the other hand, in the third embodiment, the temperatures of the controllable electric valves having different current loads in the switching mode, for example, the controllable electric valves Q1 and Q3 are detected and the temperature is equalized so that the temperatures are equalized. To switch the switching mode. This is more practical value in that the temperature difference of the final target to be equalized is detected and fed back to control. That is, even if the current load of each controllable electric valve becomes uniform, the actual hardware, for example, the cooling conditions differ somewhat depending on each controllable electric valve, which may cause variations in temperature rise. By switching the switching mode according to the temperature difference, the goal of uniform temperature rise can be more reliably realized.
[0029]
Next, a specific control operation will be described. In the case of the method of switching between the forward rotation mode and the reverse rotation mode of the first embodiment, the controllable electric valves Q1 and Q2 have substantially the same temperature, and the controllable electric valves Q3 and Q4 have substantially the same temperature. 10 (a), for example, the temperature sensors 470 and 471 detect the temperatures of the controllable electric valves Q1 and Q3, the subtractor 472 calculates the temperature difference ΔT, and this is used as a hysteresis comparator as a hysteresis comparison means. Input to 473.
The hysteresis comparator 473 has output characteristics as shown in FIG. In other words, in this example, when the temperature difference ΔT between the controllable electric valves Q1 and Q3 changes and becomes + 5 ° C. or higher, the Boolean value of the hysteresis comparator 473 is changed from 0 to 1, and when −5 ° C. or lower, 1 History operation from 0 to 0. The change in the Boolean value is detected by pulse differentiation circuits 474 and 475, and a switching mode switching signal TEMP is obtained from the OR476 output of the two differential pulses.
[0030]
In FIG. 11, the flip-flop FR is triggered by the rising edge of the signal TEMP, and the switching mode switching command R^*Inverts the Boolean value of and switches the operation mode. In this example, the forward rotation mode and the reverse rotation mode are switched. The switching timing is synchronized with the rising edge of the switching state signal S1 as described with reference to FIG. Since other parts are the same as those in the first embodiment, the description thereof will be omitted.
[0031]
Since it is configured as described above, for example, during operation in the forward rotation mode of the delayed power factor shown in FIG. 14, the temperature of the controllable electric valve Q1 rises with respect to the controllable electric valve Q3, and the temperature difference ΔT Becomes + 5 ° C. or more, the output of the hysteresis comparator 473 changes from 0 to 1, the flip-flop FR is inverted by the differential pulse TEMP, and the switching mode is switched to the reverse mode. As a result, this time, the current load shown in FIG. 15 occurs and the temperature of the controllable electric valve Q3 rises. As a result, the temperature difference ΔT decreases. When the temperature difference ΔT falls below −5 ° C., the output of the hysteresis comparator 473 changes from 1 to 0, switches to the forward rotation mode again, the temperature of the controllable electric valve Q1 rises, and the temperature difference becomes + Increase in the direction. By repeating this operation, the temperature difference between the controllable electric valves Q1 and Q3 is within a range of ± 5 ° C. without an unstable hunting operation.
[0032]
In the example shown in FIG. 10, the temperature difference between the controllable electric valves Q1 and Q3 is detected, but the average temperature of the controllable electric valves Q1 and Q2 and the controllable electric valve at which the current loads are almost equal to each other. You may make it detect the temperature difference with the average temperature of Q3 and Q4.
When switching between the mode A and the mode B described in the second embodiment, the temperature difference between the controllable electric valves Q1 and Q2 or the average temperature of the controllable electric valves Q1 and Q3 and the controllable electric valve Q2 And a temperature difference from the average temperature of Q4 may be detected.
Furthermore, the hysteresis comparator may be replaced with software that performs a similar history comparison operation. The ± operating point is not limited to 5 ° C., and can be set to an appropriate value in consideration of the time constant of the temperature rise of the controllable electric valve, detection error, and the like.
[0033]
As described above, in the third embodiment, since the switching mode is switched according to the detected temperature difference of the controllable electric valve, the temperature rise of each controllable electric valve is more reliably realized. This improves the utilization rate of the controllable electric valve.
[0034]
In the above description, the single-phase bridge inverter having the main circuit configuration shown in FIG. 12 has been described as an example. However, the present invention includes the single-phase bridge inverter as a constituent element, a plurality of units, and a converter. The present invention can be applied to a dc / dc converter, a three-phase reactive power control device, and the like configured by combining a transformer, a transformer, and the like with the same effects.
[0035]
【The invention's effect】
As described above, the single-phase bridge inverter according to claim 1 of the present invention includes the first and third controllable electric valves whose anodes are connected to the DC-side positive terminal, respectively, and the cathodes that are connected to the DC-side negative terminal. And a second controllable electric valve connected to the cathode of the first controllable electric valve and an anode of the second controllable electric valve to one of the AC side terminals, The controllable electric valve 3 and the anode of the fourth controllable electric valve are connected to the other of the AC side terminals, and feedback diodes are anti-parallel to each of the first to fourth controllable electric valves. In the connected single-phase bridge inverter,
Among the above controllable electric valves, S1 is a state in which the first and fourth controllable electric valves are turned on, S2 is a state in which the first and third controllable electric valves are on, S2, second and third When the state of turning on the controllable electric valve is set to S3, and the state of turning on the second and fourth controllable electric valves is set to S4,
The first mode that switches in the order of S1, S2, S3, S4, S1,... And the second mode that switches in the order of S1, S4, S3, S2, S1,. Since it did in this way, the average electric current burden of each controllable electric valve is equalized, and the utilization factor of a controllable electric valve improves.
[0036]
A single-phase bridge inverter according to claim 2 of the present invention is
The first mode that switches in the order of S1, S2, S3, S2, S1, and so on and the second mode that switches in the order of S1, S4, S3, S4, S1,. Since it did in this way, the average electric current burden of each controllable electric valve is equalized, and the utilization factor of a controllable electric valve improves.
Further, by alternately using mode A in which the virtual neutral point potential of the load is biased positively and mode B in which the virtual neutral point potential of the load is negatively biased, the virtual neutral point potential of the load becomes 0 on average. The problem of uneven load potential is also eliminated.
[0037]
In addition, since the single-phase bridge inverter according to claim 3 of the present invention switches between the first and second modes every predetermined number of cycles, the mode can be switched with a simple control configuration.
[0038]
  A single-phase bridge inverter according to claim 4 of the present invention isDetecting the difference between the temperature of one or both of the first and second controllable electric valves and the temperature of either or both of the third and fourth controllable electric valves;
Since the mode is switched according to the polarity of the temperature difference so that the absolute value of the temperature difference is reduced, the temperature rise of each controllable electric valve is surely made uniform, and the utilization rate of the controllable electric valve is further improved. .
A single-phase bridge inverter according to claim 5 of the present invention isDetecting the difference between the temperature of one or both of the first and third controllable electric valves and the temperature of either or both of the second and fourth controllable electric valves;
  Since the mode is switched according to the polarity of the temperature difference so that the absolute value of the temperature difference is reduced, the temperature rise of each controllable electric valve is surely made uniform, and the utilization rate of the controllable electric valve is further improved. .
[0039]
  Further, the claims of the present invention6The single-phase bridge inverter according to the present invention includes a hysteresis comparison unit that inputs a detected temperature difference and performs a history operation using a predetermined positive / negative temperature difference as an operating point, and switches the mode based on an output signal of the hysteresis comparison unit. Unstable hunting operation due to change is prevented, and stable mode switching operation is realized.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining a basic concept of a control method for a single-phase bridge inverter according to Embodiment 1 of the present invention;
FIG. 2 is a circuit configuration diagram for creating a switching signal for each controllable electric valve Q1 to Q4.
FIG. 3 is a circuit configuration diagram continuing from FIG. 2;
4 is a timing chart showing signal waveforms at various points in FIGS. 2 and 3. FIG.
FIG. 5 is a diagram showing current waveforms of controllable electric valves Q1 to Q4 and feedback diodes D1 to D4 when mode switching is performed.
FIG. 6 is a diagram illustrating a basic concept of a control method for a single-phase bridge inverter according to a second embodiment of the present invention.
7 is a diagram showing current waveforms of controllable electric valves Q1 to Q4 and feedback diodes D1 to D4 when switching is performed in mode A of FIG. 6;
8 is a diagram showing current waveforms of controllable electric valves Q1 to Q4 and feedback diodes D1 to D4 when switching is performed in mode B of FIG. 6;
FIG. 9 is a diagram showing current waveforms of controllable electric valves Q1 to Q4 and feedback diodes D1 to D4 when mode switching is performed.
FIG. 10 is a circuit configuration diagram showing a switching control system of a single-phase bridge inverter according to Embodiment 3 of the present invention.
FIG. 11 is a circuit configuration diagram continuing from FIG. 10;
FIG. 12 is a diagram showing a main circuit configuration of a single-phase bridge inverter.
FIG. 13 is a diagram illustrating a conventional switching mode.
14 is a diagram showing current waveforms of controllable electric valves Q1 to Q4 and feedback diodes D1 to D4 when switching is performed in the forward rotation mode of FIG. 13;
15 is a diagram showing current waveforms of controllable electric valves Q1 to Q4 and feedback diodes D1 to D4 when switching is performed in the reverse rotation mode of FIG. 13;
[Explanation of symbols]
Q1-Q4 controllable electric valve, D1-D4 feedback diode, Ed DC power supply,
U1, U2 AC side terminal, S1-S4 switching state signal,
470,471 temperature sensor, 472 subtractor,
473 Hysteresis comparator.

Claims (6)

The first and third controllable electric valves whose anodes are respectively connected to the DC side positive terminals, and the second and fourth controllable electric valves whose cathodes are respectively connected to the DC side negative terminals. A cathode of the controllable electric valve and an anode of the second controllable electric valve are connected to one of the AC side terminals, and a cathode of the third controllable electric valve and an anode of the fourth controllable electric valve In a single-phase bridge inverter in which a feedback diode is connected in antiparallel to each of the first to fourth controllable electric valves,
Among the above controllable electric valves, the state in which the first and fourth controllable electric valves are turned on is S1, the state in which the first and third controllable electric valves are on is S2, the second and third When the state of turning on the controllable electric valve is set to S3, and the state of turning on the second and fourth controllable electric valves is set to S4,
The first mode that switches in the order of S1, S2, S3, S4, S1,... And the second mode that switches in the order of S1, S4, S3, S2, S1,. A single-phase bridge inverter characterized by the above. The first and third controllable electric valves whose anodes are respectively connected to the DC side positive terminals, and the second and fourth controllable electric valves whose cathodes are respectively connected to the DC side negative terminals. A cathode of the controllable electric valve and an anode of the second controllable electric valve are connected to one of the AC side terminals, and a cathode of the third controllable electric valve and an anode of the fourth controllable electric valve In a single-phase bridge inverter in which a feedback diode is connected in antiparallel to each of the first to fourth controllable electric valves,
Among the above controllable electric valves, the state in which the first and fourth controllable electric valves are turned on is S1, the state in which the first and third controllable electric valves are on is S2, the second and third When the state of turning on the controllable electric valve is set to S3, and the state of turning on the second and fourth controllable electric valves is set to S4,
The first mode that switches in the order of S1, S2, S3, S2, S1, and so on, and the second mode that switches in the order of S1, S4, S3, S4, S1,. A single-phase bridge inverter characterized by the above.   The single-phase bridge inverter according to claim 1 or 2, wherein switching between the first and second modes is performed every predetermined number of cycles. Detecting the difference between the temperature of one or both of the first and second controllable electric valves and the temperature of either or both of the third and fourth controllable electric valves;
2. The single-phase bridge inverter according to claim 1, wherein the mode is switched according to the polarity of the temperature difference so that the absolute value of the temperature difference is reduced . Detecting the difference between the temperature of one or both of the first and third controllable electric valves and the temperature of either or both of the second and fourth controllable electric valves;
The single-phase bridge inverter according to claim 2, wherein the mode is switched according to the polarity of the temperature difference so that the absolute value of the temperature difference is reduced . 6. The hysteresis comparison means for inputting a detected temperature difference and performing a history operation using a predetermined positive / negative temperature difference as an operating point, and switching modes based on an output signal of the hysteresis comparison means. Single phase bridge inverter.

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