• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    This invention proposes a soft-switching modulation of single-phase quasi-Z-source rec- tifier without auxiliary circuit. This invention solves the problems that an auxiliary resonant circuit are needed and power switches with higher voltage capacity are also needed. The modulation is achieved based on a single-phase quasi-Z-source rectifier. A switch S7 is a quasi-Z-source power switch. Switches S1-S4 are four power switches in a controlled rectifier H bridge. When the switch S7 is turned off, the system works in shoot-through state. When the switch S7 is turned on, the system works in non-shoot-through state. In shoot-through state, a quasi-Z-source inductor discharges a quasi-Z-source capacitor through free-wheeling diodes in the H bridge. The free-wheeling diodes are turned on, so the voltage across each power switch in the H bridge is clamped to zero. The power switches can be turned on and turned off in a zero-voltage switching manner. When the currents of the quasi-Z-source inductors work in critical or discontinuous state, each switch can be turned on and turned off in the zero-voltage switching manner or a zero-current switching manner. The modulation proposed in this invention can achieve the soft-switching technology without any auxiliary circuit only by designing a proper quasi-Z-source inductance.
    公开号:NL2025066A
    申请号:NL2025066
    申请日:2020-03-05
    公开日:2020-09-11
    发明作者:Zhang Qianfan；Na Tuopu；Dong Shuai；Qu Jianzhen；Wang Jinxin；Yuan Xue
    申请人:Harbin Inst Technology；
    IPC主号:
    专利说明:

    110-884-233 SOFT SWITCHING MODULATION OF SINGLE-PHASE QUASI-Z-SOURCERECTIFIER WITHOUT AUXILIARY CIRCUIT
    TECHNICAL FIELD The proposed invention relates to a modulation of a single-phase rectifier, and specifical- ly to a soft-switching modulation of a quasi-Z-source rectifier.
    BACKGROUND When the soft-switching technology is not applied, each power switch of single-phase rectifier exists switching losses when switching state changes. To solve this problem, an aux- iliary resonant circuit is added. Using the resonant circuit, a power switch can be turned off in a zero-voltage switching manner. However, the resonant circuit has remarkable defects, and its working principle makes the voltage resonant. Even though the voltage across a power switch can be equal to zero, the maximum resonance voltage is higher than the DC-side volt- age, so the voltage across a power device increases. Therefore, an auxiliary resonant circuit and a power device with higher voltage capacity are needed so as to increase the cost and the size of the system.
    SUMMARY The objective of this invention is to propose a soft-switching modulation of single-phase quasi-Z-source rectifier without auxiliary circuit which can solve the problems that an auxil- 1ary resonant circuit and power switches with higher voltage capacity are needed.
    This invention 1s achieved based on a single-phase quasi-Z-source rectifier. The process- es of the modulation are as follows: at ti, the switch S7 is turned on, and a rectifier system works in non-shoot-through state. At t2, the switch S7 is turned off, the rectifier system works in shoot-through state. The switch S; is turned on and the switch Sz is turned off at the same time. In shoot-through state, the diode Di and D; are turned on, and the voltage across the switch S| and the switch S: are clamped to zero, so the switch Sy and the switch S; can be turned on and turned off in a zero voltage switching (ZVS) manner. In shoot-through state, the inductor current of a quasi-Z-source network decreases to zero. At t3, the switch S7 is turned on, the inductor current of the quasi-Z-source network is zero, so the current through switch S7 is zero. During the period t3 to t4, the rectifier system works in non-shoot-through state, and the inductor current of the quasi-Z-source network increases. At ts, the switch S7 is turned off, the switch Ss is turned on and the switch S4 is turned off at the same time. Free- wheeling diodes D3 and D4 clamp the voltages across the switches Ss and Ss to zero. The switches can be turned on and turned off in the ZVS manner. At ts, the inductor current of the quasi-Z-source network decreases to zero, and the free-wheeling diode Ds is turned off. At ts,
    the switch S7 is turned off, the rectifier system works in shoot-through state, all free-wheeling diodes are turned on and clamp the voltages across the switches Sz, S3 and Si to zero, no cur- rent flows through the switches Si, S: and Ss. So all switches can be turned on and turned off in a zero current switching (ZCS) manner or the ZVS manner. The processes are finished in one switching period and cycled. This invention proposes a novel modulation for the single-phase quasi-Z-source rectifier. The currents of the quasi-Z-source inductors work in critical state or discontinuous state, so each switch can be turned on or turned off in the ZVS or ZCS manner. This invention can achieve the soft-switching technology without any auxiliary circuit only by designing a prop- er quasi-Z-source inductance. Each power switch of the single-phase quasi-Z-source rectifier can be turned on and turned off in the ZVS or ZCS manner by using the proposed modulation with the minimum cost. As the currents of the quasi-Z-source inductors work in critical or discontinuous state, the inductance is small. Therefore, this invention can achieve the soft- switching technology of the single-phase quasi-Z-source rectifier and reduces cost, volume and space of the system. According to this invention, no auxiliary circuit is utilized, each switch of the single-phase quasi-Z-source rectifier can be turned on and turned off in the ZVS or ZCS manner. The maximum voltage across the power switch is not higher than the DC- side voltage, and the switches with higher voltage capacity are not needed. The modulation proposed in this invention is not based on the resonance principle, so the voltage across each power switch is equal to the DC-side voltage. Therefore, this invention can be widely applied to various controlled rectifier circuits.
    BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a topology of a single-phase quasi-Z-source rectifier. FIG. 2 is an operating time sequence diagram of switches of a modulation proposed in this invention. FIG. 3 1s a schematic diagram showing current and voltage waveforms of each switch in one switching period. FIG. 4 is a diagram showing an equivalent circuit of a quasi-Z-source network in non- shoot-through state. FIG. 5 is a diagram showing an equivalent circuit of a quasi-Z-source network in shoot- through state.
    DETAILED DESCRIPTION Embodiment 1: the embodiment is illustrated with reference to FIG. 1, FIG. 2 and FIG. 3. The modulation proposed in this invention is based on the single-phase quasi-Z-source recti-
    fier. The topology of the single-phase quasi-Z-source rectifier is formed of an AC source X, an inductor Ls, a rectifier H bridge, a quasi-Z-source network circuit, an output capacitor Co and an output resistor R. The rectifier H bridge is formed of the switch Si, the switch Ss, the switch S3, the switch Sy, the diode Dy, the diode D3, the diode Ds and the diode D4. The quasi- Z-source network circuit is formed of an inductor Li, an inductor L:, a capacitor C1, a capaci- tor Cz and a switch Sz.
    One output end of the AC source X is connected with one end of the inductor Ls, the oth- er end of the inductor Ls is connected with the source of the switch Si, the drain of the switch Ss, the positive electrode of the diode Dy and the negative electrode of the diode D2; another output end of the AC source X is connected with the source of the switch Ss, the drain of the switch Ss, the positive electrode of the diode Ds and the negative electrode of the diode Ds. The drain of the switch Si, the drain of the switch Ss, the negative electrode of the diode Dy and the negative electrode of the diode Ds are connected with one end of the capacitor C and one end of the inductor Li; the other end of the inductor L; is connected with one end of the capacitor C2 and the drain of the switch S7; the other end of the capacitor C; is connected with one end of the output capacitor Co, one end of the output resistor R, the source of the switch Ss, the source of the switch Ss, the positive electrode of the diode D2 and the positive elec- trode of the diode Dy; the other end of the capacitor C: is connected with the source of the switch S; and one end of the inductor L:; the other end of the inductor L; is connected with the other end of the output capacitor Co and the other end of the output resistor R.
    The processes of the modulation are as follows: at ti, the switch S7 is turned on, and the rectifier works in non-shoot-through state. At t>, the switch S7 is turned off, the rectifier sys- tem works in shoot-through state, the switch Si is turned on and the switch Sz is turned off at the same time. In shoot-through state, the free-wheeling diodes D; and D: are turned on, and the voltage across the switch Si and the switch Sq are clamped to zero, so the switch Sy and the switch Sz are turned on and turned off in a ZVS manner. In shoot-through state, the induc- tor current of the quasi-Z-source network always decreases to zero; at t3, the switch Sy is turned on, the inductor current of the quasi-Z-source network is zero. So the current of the switch S7 is zero. During period t3 to ts, the rectifier system works in non-shoot-through state, and the inductor current of the quasi-Z-source network increases. At ty, the switch S; is turned off, the switch Ss is turned on and the switch S4 1s turned off at the same time. The free- wheeling diodes Ds and D: clamp the voltage across the switches Ss; and Si to zero. The switches can be turned on and turned off in the ZVS manner. At ts, the inductor current of the quasi-Z-source network is zero, and the free-wheeling diode Ds is turned off. At ts, the switch
    S7 1s turned off, the rectifier system works in the shoot-through state, all free-wheeling diodes are turned on and the voltages across the switches Sz, Sz and Ss are clamped to zero, no cur- rent flows through the switches Si, S: and Ss. So all switches can be turned on and turned off in the ZCS or ZVS manner. During the processes, no switching losses exist and the full soft- switching can be achieved.
    One switching period is one carrier wave period. This is because the applied carrier wave is a triangle wave, and all switch states change according to the comparison of a modulation wave and the carrier wave in one triangle carrier wave period, which is also called the switch- ing period.
    The quasi-Z-source network has two working states, namely the shoot-through state and the non-shoot-through state. In shoot-through state, the switch S7 is turned off. In non-shoot- through state, the switch Ss is turned on. The current value of the inductor L; and the current value of the inductor L: are equal to each other in shoot-through state and non-shoot-through state. In FIG. 2, It is the current value of the inductor L; and the inductor Ls.
    FIG. 4 is a diagram showing the equivalent circuit of a quasi-Z-source network in non- shoot-through state. FIG. 5 is a diagram showing the equivalent circuit of the quasi-Z-source network in shoot-through state. Firstly, an expression of the voltage across the inductors can be got according to current changes of the inductors: PF gr | he as (0.1) Le Et, dt In non-shoot-through state, there are the expressions: ( LEE, =v EE (og [1,8 = Wa = Ve Ve In shoot-through state, there are the expressions: | bay == he (0.3) {2,5 =e = Vy Vo In one switching period, supposing T as the total working time of the system in non- shoot-through state and BT as the total working time of the system in shoot-through state. The following expressions can be obtained according to the inductor volt-second balance re- lationship: | a= LF (0.4) VoVo 1-83
    The expression (0.4) is substituted into the expressions (0.2) and (0.3). It obtains that the system in shoot-through state and non-shoot-through state all meets the condition ViL1i=Vr:. Therefore, when the quasi-Z-source inductances are equal to each other, namely L=L,, the current ip is equal to the current ir2 according to the expression (0.1). 5 When the quasi-Z-source inductances are designed, the inductor currents of the quasi- Z-source network can work in critical or discontinuous state.
    权利要求:
    Claims (9)
    [1]
    Soft-switching modulation of single-phase quasi-Z-source rectifier without auxiliary circuit, the processes of the modulation being as follows: at ty, a switch S + is turned on, and a rectifier operates in non-overshoot state; at t2, the switch S7 is turned off, the rectifier system operates in an overshoot state, at the same time a switch Si is turned on and a switch S: is turned off; in overshoot condition, free-wheeling diodes Di and D; are turned on, and the voltages across the switch Si and the switch S: are clamped to zero so that the switch Si and the switch S: can be turned on and off in a zero voltage switching (ZVS) manner; in overshoot condition, the inductor current of a quasi-Z source network drops to zero; at t3 the switch S; is turned on, and the quasi-Z source network inductor current is zero, so that the current through the switch S7 is zero; at the time period ts - ts the rectifier system is operating in the non-overshoot state, and the inductor current of the quasi-Z source network rises, at t4 the switch 5; is switched off, at the same time a switch S; is turned on and a switch S4 is turned off; the freewheeling diodes Ds; and Da clamp the voltages across switches S3 and S4 to zero; the switches can be turned on and off in the ZVS way; at ts the inductor current of the quasi-Z source network is zero, and the free-wheeling diode Ds is turned off; at t7, the switch is turned off, the rectifier system operates in overshoot condition, all freewheeling diodes are turned on and the voltages across switches Sz, S3 and S4 are clamped to zero, and no current flows through switches Si, S2 and Si, so that all switches can be turned on and off in a zero current switching (ZCS) manner or the ZVS manner; whereby the processes are completed in one switching period and are repeated several times.
    [2]
    The soft-circuit modulation of single-phase quasi-Z-source rectifier without auxiliary circuit according to claim 1, wherein the topology of the single-phase quasi-Z-source rectifier is formed from an AC source X, a
    -7- inductor Ls, a rectifier H-bridge, a quasi-Z source network circuit, an output capacitor Co and an output resistor R; the rectifier H-bridge is formed of the switch S1, the switch S1, the switch Ss, the switch Ss, the diode Di, the diode D2, the diode Ds and the diode D4; a circuit of the quasi-Z-source network is formed of an inductor Li, an inductor L », a capacitor C1, a capacitor C 1 and the switch Sv; an output end of the AC source X is connected to one end of the inductor Ls, the other end of the inductor Ls is connected to the source of the switch Si, the drain of the switch S i, the positive electrode of the diode Di ; and the negative electrode of the diode D1; another output end of the AC source X is connected to the source of the switch Sz, the drain of the switch S4, the positive electrode of the diode D3 and the negative electrode of the diode Dy; the drain of the switch Si, the drain of the switch Ss, the negative electrode of the diode Di and the negative electrode of the diode D; connected to one end of the capacitor Ci and one end of the inductor Li; the other end of the inductor Li is connected to one end of the capacitor C 1 and the drain of the switch Sz; the other end of the capacitor C: is connected to one end of the output capacitor Co, one end of the output resistor R, the source of the switch S », the source of the switch Si, the positive electrode of the diode D: and the positive electrode of the diode Dy; the other end of the capacitor Ci is connected to the source of the switch S; and one end of the inductor Ly; the other end of the inductor L: is connected to the other end of the output capacitor Co and the other end of the output resistor R.
    [3]
    The soft-switching modulation of single-phase quasi-Z-source rectifier without auxiliary circuit according to claim 1, wherein the switching period is a carrier wave period. A4. Soft-switching modulation of single-phase quasi-Z-source rectifier without auxiliary circuit according to claim 1, wherein the overshoot condition is that the switch S7 is turned off.
    [4]
    -8-
    [5]
    The soft-circuit modulation of single-phase quasi-Z-source rectifier with no auxiliary circuitry according to claim 1, wherein the no-overshoot condition is that the switch S7 is turned on.
    [6]
    The soft switching modulation of single phase quasi-Z source rectifier without back-up circuit according to claim 3, wherein the carrier wave is a triangle wave.
    [7]
    A soft-circuit modulation single-phase quasi-Z-source rectifier without auxiliary circuit according to claim 4 or claim 5, wherein the current values of the inductors Li and L: in the overshoot and no overshoot conditions are equal to each other.
    [8]
    A soft-circuit modulation single-phase quasi-Z-source rectifier with no auxiliary circuit as claimed in claim 2, wherein the inductance of the inductor is L; is equal to the inductance of the inductor L:.
    [9]
    The soft-circuit modulation of single-phase quasi-Z source rectifier without back-up circuit according to claim 1, wherein the currents from the quasi-Z source network inductors operate in a critical state or intermittent state.
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