TWI261408B - High-efficiency modified phase-shift-modulation technique - Google Patents

Abstract

A high-efficiency modified phase-shift-modulation technique is proposed in this text. The proposed phase-shift-modulation technique can be applied in the design of dc-ac single-phase full-bridge inverter. Using the proposed technique, zero-voltage-switching of the power switches can be achieved. The advantages of the proposed technique include: lower switching stresses; lower switching losses, increase conversion efficiency; lower electromagnetic interference (EMI); no additional circuit required, controller is easy to implement.

Description

1261408 IX. Description of the invention: [Technical field to which the invention pertains] The present invention relates to the technical field of the method of _ _ traditional money-AC single-phase full-bridge _ (four), especially the switching operation of the frequency converter to soft switching The state, the efficiency, the required rating of the switching components, the electromagnetic interference caused by switching switching, and the switching frequency of the i liter. Ding Ren: Right [Previous Technology] According to the rapid development of semiconductor technology of integrated circuits, system designers and electronic product manufacturers are particularly characterized by light, thin, short and small. In order to avoid audio, the high-frequency switching inverters are rarely read more than z. If the traditional Hard Switching method is used, the #frequency increase of the day-to-day crystal is before the guidance. (T_(4) switching loss will increase, so the loss of power crystal will increase, and a large heat sink is needed, which not only increases the volume but also reduces the efficiency. In order to effectively reduce the switching loss and improve the system efficiency, Soft switching (s〇ft (four) ice (four) has become a technology that is currently used in various power electronic products. The figure _ is a schematic diagram of the power switch using a hard-cut method.] If the power switch 7G is used for switching, the hard-cut method is used. When the switch is turned off, the voltage v across the 汲-source (Dram-Source) will still rise rapidly and produce an electric dust rush wave whose value will exceed the input voltage value of the positive bearing (V-like). Will increase the voltage stress of the power component, and when the switch τ is turned on, the switching element is affected by the output capacitance of the body, so the current will generate a larger current surge than the normal current, thus increasing The current stress of the power component. When the power switching component is not turned on or off, it is not a non-zero voltage or a non-zero current, and a sharp wave will cause a power consumption of 4, which will cause the switching of the power switching element when commutating. The loss is shown in the first figure. As shown in the second figure, the voltage and current changes of the power switching element are traced during hard cutting. As can be seen from the second figure, 'the current begins to circulate after the power element is turned on. Time (D, due to the influence of the output capacitance of the opening and the stray capacitance on the line, a current spike will be generated, but at this time, the L of the 1261408 Y _ component voltage is still high, and its value is the rate switch. When the component rises (t) during the turn-on time, the input voltage v〆 of the operation is “when the power is turned off, the current begins to decrease.”: There is power consumption in the middle of the operation; otherwise, the switching component is fast in the cut L. Soaring and generating - voltage two!?, there is no source (Drain-source) voltage zero across, so the power switching element drops at the cutoff ^ ^ related components of the current 匕 has not yet fallen to the front side of the guard (M Same as The success rate is consumed. The second figure is not the power switch soft cut P, /1 X , ^ 0a do not think about it, (a) voltage and current wave pattern trace diagram (6) power switch voltage and current waveform diagram it 甶In the second figure, it can be seen that the power switching element is in the rise time of the conduction, the rear, the electric, and the "1L" (m lL ^, because the power switching voltage is at zero potential, it is called zero voltage exchange (ZVS); When the field knife switch is turned off, the current reaches zero value, and 1 turn sorrow rises. This behavior is called zero current exchange (zcs). The exchange loss is greatly reduced, thus improving the overall efficiency of the inverter. The main difference between switching and soft switching is the situation at the time of switching. The differences are as follows: · Hard switching Soft switching When the switching element is turned on or off, the switching element must withstand all voltages and flow through the full load. Current. When the switching element is turned on or off, the switching element is at zero voltage (or zero current), so the switching loss is very low. The diode recovery effect and stray inductance increase the stress and loss of the switch. There is no diode recovery effect and the stray capacitance does not cause unwanted effects. The switching track is close to the edge of the safe area. The switching track retreats from the edge of the safe area. High electromagnetic interference. Low electromagnetic interference. In high-frequency operation, the component needs to be derated due to the switching loss. -------- ---- It is possible to operate at higher frequencies. The soft switching techniques applicable to DC-AC inverters can be roughly divided into the following three according to their architecture.

6 1261408 is a soft switching method for adding a hybrid network to the load side, a weight switching method for adding a spectral network to the inverter bridge arm, and a soft switching method for adding a resonant network to the DC link side. The age description is as follows: Soft switching method for adding a resonant network on the load side: Soft switching method for adding a resonant network on the load side and depending on the resonant network to be added is a string-ear white-shock network or a parallel resonant network Sort it. In a series resonant network architecture, the bridge arm of the frequency converter delivers the square wave voltage to the series resonant network. σ f C. Schwarz, method of resonant current pulse _ modulation fQr pQwer CQnverters,,,iEEE Trans· 〇n

Electronics, Control and Instrument, Vol. IECI-17, pp. 209 - 221, June 1970. Proposed by Kifune, H.; Hatanaka, Y.; Nakaoka, M.;

Quasi-series-resonant-type soft-switching phase shift modulated inverter, IEE Proceedings-Electric Power Applications, Volume: 150,

Issue: 6,7 Nov·2003, Pages: 725-732) for the formation of a series connection between the load and the series resonant network; conventional technology (N·Mapham, “An SCR converter with good regulation and sine-wave output” , IEEE Transactions on. Industrial Generation Application, Vol· IGA-3, pp .176 - 187, Mar./April 1967·, Chien-Ming Wang;丨'Nonlinear-controlled strategy for soft-switched

Series-resonant DC/AC inverter without auxiliary switches11, IEEE

Transactions on Power Electronics, Volume: 18, Issue: 3, May 2003,

Pages: 764 - 774 proposed) to form a parallel structure for the load and the series resonant network. The series resonant network method uses the series resonance to achieve the purpose of zero current switching. Therefore, the main limitation is that the switching frequency cannot be higher than the resonant frequency. When the resonant frequency drifts due to aging or production inconsistency of components, the output voltage or current The adjustability will be worse. 1261408 In a parallel resonant network architecture, the bridge arm of the frequency converter delivers square wave current to the parallel resonant network. Conventional technology (J. G. Kassakian, "A new current mode sine wave inverter," IEEE Transactions on Industrial Applications, Vol. 18, pp. 273-278, May/June 1982, by V. Chudnovsky, B. Axelrod, and AL Shenkman, "An approximate analysis of a starting process of a current source parallel inverter with a high-Q induction heating load," IEEE Transactions on Power Electronics, Vol. 12, pp. 294 - 301,

Mar. 1997) "Current-source parallel resonant DC/AC inverter with transformer," On Power Electronics, Vol. 11, PPe 275 - 284, Mar. 1996) is a structure in which the load is connected in parallel with the parallel resonant network. Since the parallel resonant network causes an alternating voltage on the switch, the power switch must have It has the ability to resist the reverse voltage. If the power switch does not have this capability, it is necessary to add a blocking diode to the circuit. In addition, the resonant network can be added to the load side to achieve the purpose of soft switching. The structure of the resonant network is more suitable for the case where the load is fixed. If the load changes drastically, the effect of the spectral vibration will be worse. 2. The soft switching method of adding the resonant network to the bridge arm of the inverter: For the bridge arm of the inverter In the architecture of the resonant network, the input voltage or current of the inverter is fixed. Conventional technology (by R. Tymerski, v. Vorpzerian, andF c wDC-to-AC inversion using quasiresonant techniques, ^ Transactions on Power Electronics, Vol. 4, pp. 381 - 390, Oct. 1989^4) ^ Architecture of Resonant Zero-Voltage Switching Mode 'To achieve zero voltage switching effect The current resistance required for the switch of this method will increase, and the method will be affected by the value of the output inductance. In some inductance values; it is not easy to achieve zero voltage switching effect at 1261408. Finally, this method is not applicable to outputs such as motor control. For the case of an inductor ** load. Conventional technology (by J.-S. Lai, R. WYoung, G. W. 〇tt, Jr., JW McKeever, and FZ Peng, delta-configured auxiliary resonant snubber inverter, ', IEEE Transactions on· Industrial Applications, Vol. 32, pp. 518-525, May/June 1996_ proposed by Smith, KM·, Jr.; Smedley, KM.; ^Lossless passive soft-switching methods for inverters and Amplifiers, IEEE Transactions on Power Electronics, Volume: 15, Xinsue·1, Jan. 2000, Pages: 164-173) Using soft-shock circuits to achieve soft switching The purpose of this type of circuit is that it can be used with the pulse width modulation method, but such a method must be added with a passive cushioning unit, thereby increasing the complexity of the circuit. Conventional Technology (by Smith, LM, Jr.; Smedley, Κ·Μ·; "InteUigent magnetic ^ amplifier - controlled soft-switching method for amplifiers and inverters", IEEE Transactions on Power Electronics, Volume: 13,

Issue: 1,jan. 1998, Pages: 84-92 proposed to add a resonant circuit to the inverter bridge to achieve the effect of soft switching. The paving method requires an external auxiliary switch and a resonance including the spectral passive component X. Circuits, which increase the cost. In summary, the soft switching method of adding the resonant bridge to the resonant network is mostly achieved by using an auxiliary switch. The principle is that if the zero voltage switching is to be achieved, the input end and the load need to form a parallel resonant network when the auxiliary switch is turned on. If the zero current switching is to be achieved, the input terminal and the load need to form a series resonant network when the _ help switch is turned on. At the same time, the control timing of the auxiliary switch must be specially set and counted, which also increases the complexity of the circuit implementation. 3. Soft switching method for adding spectral network to the DC link side·· The soft switching method for adding the resonant network to the DC link side can be divided into two categories: voltage/current on the DC link side and AC waveform or DC waveform. 9 1261408 Conventional Technology (Ρ·Κ·Sood and Τ·A·Lipo, “Power conversion distribution system using a high-frequency AC link,,, IEEE Transactions on Industrial Applications, Vol. 24, pp 288 - 299

Mar./Apr· 1988 proposed to use a DC link resonant network to resonate the input voltage into an AC form, thereby achieving the purpose of soft switching. The operating mode adopted by this type of architecture is the AC/AC converter mode. The disadvantage is that the switch needs to be resistant to AC voltage, and the output must be achieved by Discrete Pulse Modulation (DPM). It cannot be implemented using the most commonly used pulse width modulation method. Conventional technology (by Yie-Tone Chen; nA new quasi-parallel resonant DC link for soft-switching PWM inverters丨丨, IEEE Transactions on Power Electronics, Volume·· 13, Issue·· 3, May 1998, Pages: 427 - 435 proposed by XiangningHe; KuangSheng; Williams, BW· ; ZhaomingQian; Finney, SJ ; !fA composite soft-switching inverter configuration with unipolar pulsewidth modulation control11, IEEE Transactions on Industrial Electronics, Volume: 48, Issue: 1 , Feb. 2001, Pages: 118-126) uses a quasi-parallel resonant network on the DC link side for soft switching purposes. The DC link side voltage of the method does not reach a negative value, so the switch does not need to be resistant to AC. Voltage. This type of method is supplemented with an auxiliary switch to achieve this purpose, and the control timing of the applied switch is more complicated. As can be seen from the above, the use of the application does have its limitations. Therefore, the inventor has studied and researched the problems faced by the above-mentioned problems through years of experience in related industries, and actively sought solutions, and has been tested and improved many times. After that, an improved phase shift modulation method and a frequency converter for the single-phase DC AC frequency converter were finally invented. SUMMARY OF THE INVENTION Accordingly, the main object of the present invention is to provide an improved phase shift modulation method for a single-phase DC-AC converter, which is a method of phase modulation that will drive the power crystal on the diagonal line. 1261408 The signal is phase-shifted to achieve the purpose of soft switching, thereby reducing the loss of switching elements and the necessary cushioning circuit, improving conversion efficiency, reducing electromagnetic interference and making the switching frequency higher. In order to achieve the above object, the present invention provides a shifting modulation method applied to a single-phase DC-AC inverter, which can take into account the softness effect and can transmit a turbulent flow, which includes: a) generating a basic square wave : 5(10) This square wave generation circuit can be generated for single-phase full-bridge variation. #任周期为b) Generate phase-shifted square wave·· 幻=!-shaped circuit's duty cycle for the other arm of the inverter is proportional to the edge of the output voltage The square wave is shifted, and the center line of the phase-shifted square wave is symmetric with respect to the falling of the basic square wave described in item a. c) Defining the dead time: Using the dead-time generating circuit, the dead field can be added to the square wave described above. Time (Dead ti, to keep the wheel voltage stable. ffi (Dead time) ^ (4) External supply - touch good type single-phase full-view frequency::::: rate open _, complete -, two two #疋 inductance The output capacitance of the low-pass transistor _FET consisting of α轮) and the turn-off capacitor (co), A is the gold slope % effect. The fifth picture is the body diode of the ... 乳YANG effect transistor (B〇dy voltage feed type _ 2 1 = relay timing diagram and electric radiation (10) wheel out waveform, in which the full bridge destroys the power components, Therefore, I, when conducting 'otherwise will produce high voltage and high current burning 疋 salty ZVS, as shown in the gray area of the fifth figure. As can be seen from the fifth figure, the improved phase shift proposed by the present invention is in the paste switch B The switching waveform is kept as the responsibility cycle. The principle of the change of the principle is changed. Chen and Kai _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ The voltage that will be paid on the load: Relatively, when the switch B and the switch D (opposite to each other) are turned on at the same time, the voltage obtained by the second is loaded. Therefore, in a switching cycle, the sequential conduction is turned on, (4) There will be positive and negative voltages with different widths. Since the switching frequency of the phase shifting modulation is higher than the frequency of the AC output wave to be realized, the positive and negative voltages on the aforementioned load must be (four) Wave circuit (ie Lo and (5) in the fourth figure. When the aforementioned load voltage is positive When the duration is at a negative voltage, the "after the chopping" will be positive; when the duration of the positive voltage of the aforementioned load voltage is less than the negative voltage, the voltage after the chopping will be negative. By this mechanism The improved phase shift modulation technique proposed by the present invention will generate an alternating voltage on the output side. To achieve the above object, the present invention also provides a controller including: a basic square wave generating circuit for single phase The full-bridge inverter generates a symmetrical square wave with a duty cycle of 5〇%; the phase-shifting waveform generating circuit generates a duty cycle for the other arm of the inverter proportional to the square wave of the square to be output and the center line of the square wave Symmetrical to the falling edge of the square wave described in the & item, and the phase shift amount of the phase spear waveform is related to the output voltage; the dead time generating circuit can add the dead time time to the square wave described above; And the count ^, used to generate the aforementioned functions and time bases. Advantageously, the comparator and the counter basic time base are done in a single digit manner. The medium 4 ratio & comparator comparison and counter basic time base system Analog circuit Completed. 妾 g 列举 - 较佳 较佳 较佳 较佳 较佳 较佳 较佳 较佳 较佳 较佳 较佳 较佳 较佳 较佳 较佳 较佳 较佳 较佳 较佳 较佳 较佳 较佳 较佳 较佳 较佳 较佳 较佳 较佳 较佳 较佳 较佳 较佳 较佳 较佳 较佳 较佳 较佳 较佳 较佳 较佳 较佳 较佳 较佳 较佳And the skilled artisan can implement the present invention. The following description is only for explaining the preferred embodiments, and is not intended to limit the scope of the present invention. Therefore, the invention is based on the spirit of the invention. Any form of ^: more or modified is within the scope of the invention intended to be protected. 12 1261408 Embodiments In order to fully describe the seven (4) of each mode-modified phase-shifting modulation technique in the circuit, The formula proposed by the invention is described in detail. ^Knife into 8 working state modes, and for each mode

• Mode-1 In this interval, A and c are in the on state, and B and D畨L ^ ' are off. The current flows in a positive direction and charges the rim φ 〇 and the output capacitor (co). ! Most output power

( , , value 1 is still (t 1) is Ulp, Co voltage final value V

SLP

1 'SLP polarity is shown in Figure 6. Its output voltage v = V

• Mode - Π •• (tetstj (10), when t - ti, A is cut off, at this time 11〇 stops rising. According to Lenz's law, the Yang flowing through the inductor must maintain the flow in the same direction. At this time, the current machine is charged. The team discharges; at this time, the voltage at both ends continues to rise, and the output V(10) will drop until the body of the body of B is turned on ((1) 2), (the voltage at both ends is discharged to zero. As shown in the seventh figure.

• Mode-III After the end of the working mode II, C, the voltage drop across the two is zero (t = t 2), D, conduction, will

Vz« clamps at zero, at which point b is turned on to achieve zero voltage switching, at which point V<wi is zero. As shown in the eighth figure, 0 • Mode-IV: (t St4) The power switch C is turned off (t = t 3), at which time I still charges cc and discharges; at this time (:€ the voltage across the terminal continues to rise, Discharge to zero until the body diode Dd of D is turned on (t = t 4), as shown in Figure 9. • Mode -V: (t 4 mountain seven 5) At (t 2 t 4), DJ pass After that, D is turned on, and A and C are stopped. At this time, the energy transfer function enters the energy transfer interval of the other half cycle, and then the output inductor (Lo) and the output capacitor (Co) are charged again. The final value is I ( t 5) is I-like, the final value of co voltage is v〇> (t 5) VSLP 〇13 1261408 The polarity is as shown in the tenth figure. Its output voltage v(10)=-ν^. • Mode-VI: (t, t S t 6) When t = t 5, B is cut off and stops rising at this time. According to Lenz's law, the current flowing through the inductor must keep flowing in the same direction. At this time, the current is charged and discharged to B; The voltage continues to rise until A's body diode L turns on (t = t6), and the voltage across L discharges to zero, as shown in Figure 11. • Mode-VII: (t6stst7) After the end of the operating mode VI , (^ After the voltage drop across the two ends is zero (t = t6), L is turned on, and VDS is clamped to zero. At this time, A is turned on to achieve zero voltage switching, and V(10) is zero, as shown in Fig. 12. • Mode -vill: (t7 mountain t8) The power switch D is cut off (t = t 7), at which time Iw charges C, discharges to Cc, and when (t = t 8), charges up, (^ discharges to zero, Until the body diode of C turns on dc(t = ts), as shown in Figure 13. • Simple embodiment The full bridge phase shift zero-voltage phase-shift modulation converter is different from the control signal of the traditional PWM full-bridge inverter. It has two more control signals than the control signal of the traditional full-bridge inverter, and uses the phase shift method to control the size of the duty cycle, that is, when the conduction parts of A, C or B, D overlap, there is a ^^ The voltage falls on the output load. In order to generate such a control signal, the Phase Shift generator and the Dead Time are written on the controller to obtain the control we need. The fourteenth figure is a block diagram of the control signal generator. The following sections describe the internal parts in detail. The square wave generating circuit is normally set to a fixed output square wave under normal input voltage. The Duty of A and B is 50%, and the upper left and lower left arms of the whole bridge are reverse output. In software

(S 14 1261408 - _ead tlme must also be written when the human body is dead.) It is mainly to prevent the upper and lower system from being turned on and burned, so as to keep the output voltage stable. As shown in the fifteenth figure. • Controller internal phase shift generation circuit This design test is based on energy transfer and generation of zero voltage city (zvs) mode. Its working principle has been introduced before, and the decision of the size of the work is based on software writing. The Duty value given, where the upper and lower _ty sizes are the same ratio. The Duty size determined by the upper number is used for zero voltage switching (ie, the power switch B, c is turned on and the power switch b is turned on), that is, it is ensured that the Di〇de is turned on and then turned on again, and the power switch is turned to zero; The purpose of the lower Duty size is to determine the output v(10) turn-on (Turn 〇n) and ensure that the d-ground is turned on to turn on its power switch (ie, the power switches A, c are turned on and the power switch c is turned on). The Duty calculation is as shown in equation (1). As for the power off D, it is necessary to prevent the upper and lower arms from being turned on at the same time and burn the components, so it must be output in reverse with the upper arm power switch c, and the gray zone is the dead time and the switching time required for ZVS.

Duty〇:Number)=Duty(m)= Duty φ Duty=twf Equation 1 • Controller internal counter and comparator circuit The basic square wave generation circuit and internal phase shift generation circuit described above all require a basic time as a calculation. Basic, this is the counter inside the controller. The purpose of the comparator is to create an open _ shape for various duty cycles. For example, to generate the switching element A, the B duty cycle is 5 (10), and the input end of the comparator must be set to 1/2 of the upper limit of the counter. • The duty of the following output signal is changed to generate the switching element °cd. For the waveform of the period, the input of the comparator must be set to a value proportional to the value of the output voltage to be generated. 15 1261408 Example: In terms of a period τ, suppose ΊΜΟΟΟ, Duty=100: A is open | Τ is “Η”, |Τ is “L”; B and A are mutually inverted. For C, in the range of |T, there are 2〇%(〇1〇〇) in the range of 〇~5〇〇 as "", which is due to Duty=l〇〇, and D and (] are mutually Inverted input

The remaining range (101~500) is "L". In the range of 501 to 1000, '501 to 9GG' is ''L', and the remaining range (10)1 to 1_) is,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, (1) Duty = 〇· 8 : See Figure 17 for its output waveform. (2) Duty = 〇·6 : See Figure 18 for its output waveform. (3) Duty = 〇·4 ·· Figure 19. (4) Duty = 〇·2: See Figure 20 for the output waveform.

(4) It can be seen that when the Zhou Zhou is large, the positive voltage duration of the output Μ is negative ^ the duration is smaller, the equivalent represents the round and the dragon is positive, and the ratio is proportional to the duty cycle; The smaller the output, the positive voltage of the output _ continues to be smaller, the negative voltage continues to be longer = the greater the m, the output voltage is negative, and proportional and responsible. From the above description, the method proposed by the present invention can produce a turbulent tramp between v and 2 when the duty cycle is changed. The twenty-first figure shows the use of the method proposed by the present invention to realize the sine wave input, and it can be seen from the eleventh figure that when the duty cycle is greater than Μ, the output voltage is the positive dragon of the shell The larger the value; when the responsibility chat is less than G. 5, the output material is negative, and the duty cycle is larger, the output (four) voltage value is larger. 2 said above, the present invention _ has the above-mentioned numerous performance and real value, and can effectively improve the economic benefits of the body, so the present financial is, _, and in the marriage technology collar 16 1261408 domain did not see side or alone The public use of the product shall meet the requirements of the invention, and shall be submitted in accordance with the law and the patent of the invention shall be granted. [Simple diagram of the diagram] f - diagram of the power switch component switching electric current waveform ^ map system power · component hard cut current test current waveform trace diagram second diagram power switch component soft cut schematic diagram fourth The basic circuit structure of the improved phase-shifting single-phase full-bridge inverter is shown in Figure 5. The closed-loop control signal and the electric-radiation waveform of the switch b in the present invention. The sixth figure is the operation of the present invention in mode 1: energy transmission Schematic diagram to load: Figure 7 is a mode 11 of the present invention: power switch. The diagram of the charging and discharging path of the charging and discharging path during the conduction is the mode of the present invention • • The power half switch B, C, the conduction section of the schematic diagram of the present invention, the mode IV: the power opening thin guide, the tenth embodiment of the present invention Mode v: Energy New Circuit is only painless when it is transported to the load. The schematic diagram of the eleventh figure is the mode of the present invention. 7丨·· Power ^ ^ ^Off D-charge and discharge path of the conduction path Mode VII of the present invention: the sound of the 丄 丄 丄 开关 开关 开关 开关 开关 开关 开关 开关 开关 开关 开关 开关 开关 开关 r r r r r r : : : : : : : : : : : : : : : 功率 功率 功率 功率 功率 功率 功率Schematic diagram of the charging and discharging path of the device block wk. Figure 5 is a schematic diagram of the output signal of the switching elements A and B of the present invention. The sixteenth diagram is the switching element of the present invention, β, β, ^. ^ LD rounds the signal to signal the seventeenth system The duty cycle of the present invention D=the diagram switch switching signal and the wheel voltage waveform are shown in the eighteenth figure. The duty cycle of the invention is d=〇6 The switch switching signal and the wheel voltage waveform of the temple are shown in the nineteenth d=g. Figure off switching signal and rim waveform display FIG 171261408 twenty-based duty present invention D = 0. 2 of Time switching signal and the output voltage waveform schematic diagram of a twenty-first lines in FIG sinusoidal output voltage after a schematic view of the filter element of the present invention is mainly [Description of Symbols None

18

Claims (1)

Ϊ 261 408 Ten patent application scope · · Improved phase shift modulation method for DC-AC inverters, this method can switch effects and output AC voltage, which includes: a) Generating basic square wave: Generated by a basic square wave Circuit, ▲ 50% square wave; , ''Early phase Wangqiao inverter one arm generation responsibility cycle is b) Generate phase shift square wave · Use phase shift waveform circuit for variable size phase shift square wave, and this The phase shifting square bathing cycle is proportional to the output of the edge of the face; the centerline of the phase shifting square wave is symmetric with the falling of the basic square wave described in item a. C) Defining the dead zone time: to protect ==== Wei'er The version of the dead paste (Fu tlme) has one of the single phase one ^ symmetrical ^ wave. The skin generation circuit can generate a duty cycle of 50% H for the single-phase full-bridge inverter, for the inverter The other arm generates a duty cycle proportional to the output voltage ramp and the center line of the square wave is symmetric with respect to the falling edge of the square wave of the three terms, and the phase shift amount of the phase shift waveform is related to the output voltage; dead zone % Inter-generation circuit 'can be added in the aforementioned square wave Dead time; and comparators and counters to generate the aforementioned functions and time bases. 3. The controller of claim 2, wherein the comparator and the counter basic time base are implemented in a single wafer digital manner. 4. The controller of claim 2, wherein the comparator comparator and the counter 19 1261 408 basic time base are implemented by analog circuits. Eleven: as the next page 20 1261408 VII. Designated representative map: (1) The representative representative of the case is: (5). (2) A brief description of the component symbols of this representative figure: None 8. If there is a chemical formula in this case, please disclose the chemical formula that best shows the characteristics of the invention: