CN111934576A - Auxiliary resonance converter pole inverter with phase-correlated magnetizing current symmetric reset - Google Patents

Abstract

The invention discloses an auxiliary resonance converter pole inverter with symmetrically reset phase-correlated magnetizing current, the circuit of the invention keeps the prior art by utilizing a phase correlation method, realizes the advantage of zero-voltage switching-on of a main switch tube, reduces the switching loss of a main switch, and in addition, an auxiliary switch in an auxiliary loop also realizes the zero-voltage switching-on through energy storage in an excitation inductor and has a voltage withstanding value far smaller than that of the main switch; the magnetizing current reset is reliably realized in each switching period, and the volume of the transformer is effectively reduced; the secondary winding of the transformer is coupled to solve the problem of an auxiliary converter diode D_N1And D_N2The problem of overpressure.

Description

Auxiliary resonance converter pole inverter with phase-correlated magnetizing current symmetric reset

Technical Field

The invention relates to the technical field of power electronic conversion, in particular to an auxiliary resonance converter pole inverter with symmetrically reset phase-correlated magnetizing current.

Background

Voltage Source Inverter (VSI), which is essentially a synchronous rectification buck-boost converter formed by a fully-controlled switching half-bridge, is widely used in various power class applications, such as: motor drives, active power filters, Uninterruptible Power Supplies (UPS), photovoltaic power systems, fuel cell power systems, distributed power grids, and the like. The research core is to improve the efficiency and the power density.

Under hard switching conditions, power density is typically increased by reducing the size and weight of passive components (e.g., filter inductors and capacitors) by increasing the switching frequency, but increasing the switching frequency results in increased switching losses and high frequency electromagnetic interference (EMI), which in turn reduces the efficiency of the inverter. In VSI, the circuit is an inverter half-bridge and an inductor connected to the midpoint of the half-bridge; during hard switching, after the freewheeling mode, the energy Qrr, Qoss stored in the antiparallel diode and the output capacitor at the switching-on instant of the switching-on switching tube to be switched on is released into the channel of the switching tube, so that peak current, switching-on loss and high-frequency electromagnetic interference (EMI) are generated. One way to overcome the above problems (switching losses and EMI) is to advance the switching device technology and another is to soft switch topology technology.

Wide bandgap semiconductors such as SiC and GaN have faster turn-on and turn-off times, lower turn-off losses and lower parasitic capacitance than conventional Si power semiconductors; but faster switching times result in greater high frequency electromagnetic interference (EMI). In addition, SiC has the problems of harsh grid opening and closing conditions, high cost and the like.

Soft switching topologies can reduce switching losses and EMI at high switching frequencies. Soft switching topologies are methods to reduce switching losses by adding auxiliary circuits to decouple the transition edges of the current and voltage of the switching tubes. Among many soft switching inverter topologies, the auxiliary resonant very soft switching inverter is generally accepted because the voltage and current stresses of the switching tubes in the main circuit are not additionally increased, and the auxiliary circuit only works when the switching tubes are commutated without affecting the normal operation of the main circuit.

In the prior art, see the article "An Improved Zero-Voltage Switching Inverter Using Two Coupled Magnetics in One resistor pol" published in the 25 th volume of 2010 of IEEE Transactions on Power Electronics journal, the double-Coupled inductor (ZVT-2CI) circuit can realize Zero-Voltage Switching of a main switch and Zero-current Switching of An auxiliary switch and solve the problem that An excitation current cannot be reset. The converter diode has no clamping measure, and after the resonant current is reduced to 0, the two ends of the converter diode can bear direct-current bus voltage which is about 2 times of the voltage, and potential oscillation of the undamped end of the diode can be caused; in the prior art, the New polarity of the line phase soft switching using a dual magnetizing circuit of IEEE 201315 th European Conference on Power Electronics and Applications (EPE) can realize that the main switch zero voltage is switched on and the auxiliary switch zero current switch resets the magnetizing current by disconnecting the free flow path of the exciting current. But the diodes connected in series on the high current loop will add extra losses. In the two methods, one coupling inductor can only realize zero voltage switching-on of one main switching tube, so that two coupling inductors are required to be used in one auxiliary circuit, and the size, the cost and the leakage inductance loss of the transformer are increased.

Disclosure of Invention

In order to solve the defects of the prior art, the auxiliary resonance converter pole inverter with the phase-associated magnetizing current symmetrically reset is provided, and zero voltage switching-on of a main switch and an auxiliary switch is realized; the efficiency and the power density are effectively improved, and the cost and the EMI are reduced.

The invention provides an auxiliary resonant inverter pole inverter with symmetrically reset phase-correlated magnetizing current, which comprises a first main switch tube (S1), a second main switch tube (S2), a first converter diode (Dc1), a second converter diode (Dc2), a first freewheeling diode (Dx1), a second freewheeling diode (Dx2), a direct current power supply (VDC), an auxiliary power supply (VAUX) Load (Load), a first voltage-dividing capacitor (Cd1), a second voltage-dividing capacitor (Cd2), a resonant inductor (Lr1), an auxiliary converter transformer primary winding (T1), an auxiliary converter transformer secondary side first winding (T2), a first auxiliary switch tube (Sa1), a second auxiliary switch tube (Sa2), a third auxiliary switch tube (Sa3), a fourth auxiliary switch tube (Sa 9638), a second auxiliary switch tube (Sa2), a third auxiliary switch tube (Sa3), a fourth auxiliary switch tube (Sa4), a leading-AC Lead inductor (LmLead) and a magnetic field inductor (Sa-LmLg), the source electrode of the first main switching tube (S1) and the drain electrode of the second main switching tube (S2) are connected to a point O, and the two switching tubes form a main switching bridge arm; the drain electrode of the first main switching tube (S1), the cathode of the first commutation diode (Dc1) and the cathode of the second freewheeling diode (Dx2) are connected with the anode of a direct-current power supply (VDC); the negative pole of the direct current power supply (VDC), the source electrode of the second main switch tube (S2), the positive pole of the second commutation diode (Dc2) and the first follow currentThe anode of the pole tube (Dx1) is connected; one end of a Load (Load) is connected with a point O of the middle point of the bridge arm of the main switch, and the other end of the Load (Load) is connected with the middle points of a first voltage-dividing capacitor (Cd1) and a second voltage-dividing capacitor (Cd 2); one end of a resonant inductor (Lr1) is connected with the point O of the midpoint of the main switch bridge arm, and the other end of the resonant inductor is connected with the synonym end of the auxiliary side first winding (T2) of the auxiliary converter transformer; the dotted terminal of the auxiliary side first winding (T2) of the auxiliary converter transformer is connected with the anode of the first converter diode (Dc1) and the cathode of the first freewheeling diode (Dx 1); one end of the resonant inductor (Lr2) is connected with the point O of the midpoint of the main switch bridge arm, and the other end of the resonant inductor is connected with the synonym end of the secondary side second winding (T3) of the auxiliary converter transformer; the dotted terminal of the secondary side second winding (T3) of the auxiliary converter transformer is connected with the cathode of the second converter diode (Dc2) and the anode of the second freewheeling diode (Dx 2); the source electrode of the first auxiliary switching tube (Sa1) and the drain electrode of the second auxiliary switching tube (Sa2) are connected to a point Q, and the two switching tubes form a leading bridge arm (AC-Lang) of the commutation auxiliary circuit; the source electrode of the third auxiliary switching tube (Sa3) and the drain electrode of the fourth auxiliary switching tube (Sa4) are connected to the R point, and the two switching tubes form a hysteresis bridge arm (AC-Lead) of the commutation auxiliary circuit; the drain electrode of the first auxiliary switch tube (Sa1) and the drain electrode of the third auxiliary switch tube (Sa3) are connected with the positive electrode of the auxiliary power supply (VAUX), the negative electrode of the auxiliary power supply (VAUX) is connected with the source electrode of the second auxiliary switch tube (Sa2), and the source electrode of the fourth auxiliary switch tube (Sa 4); the dotted end of the primary winding (T1) of the auxiliary converter transformer is connected with the midpoint Q point of the leading auxiliary switch bridge arm, and the unlike end is connected with the midpoint R point of the lagging auxiliary switch bridge arm; the exciting inductance Lm is connected in parallel with two ends of a primary winding (T1) of the auxiliary converter transformer; the number of turns of a first winding (T2) and a second winding (T3) on the secondary side of the auxiliary converter transformer is the same, the number of turns of a primary winding (T1) of the auxiliary converter transformer and the turn ratio of T2 (or T3) are 1/n, and the first freewheeling diode (D)_x1) And a second freewheeling diode (D)_x2) Is applied to the first commutation diode (D)_c1) And a second commutation diode (D)_c2) Providing follow current paths for reverse current in reverse recovery process, wherein the follow current paths are respectively T₂->L_r1->S₂->D_X1->T₂And T₃->D_X2->S₁->L_r2->T₃。

As a further improvement of the above scheme, when the load current is positive, the operation mode and the switching time interval are as follows:

the circuit is in a steady state, S₂、S_a1、S_a3In the on state, S₁、S_a2、S_a4In an off state; current conversion diode D_N1、D_N2Freewheel diode D_x1、D_x2A voltage stabilizing diode D_z1、D_z2And the anti-parallel diode of the switching tube is in a turn-off state;

t₀at time, turn off S_a3；

S_a3Delay DP1 after turn-off, turn on S_a4；

S_a4Delay DP2 after switching on, turn off S₂；

S₂Delay DP3 after shutdown, turn off S_a1；

S_a1Delay DP4 after turn-off, turn on S_a2；

S_a2Delay DP5 after conduction, turn on S₁；

S₁Delay after conduction T_onTurn off S₁；

S₁Delay DP6 after turn-off, turn on S₂；

At t₀Time of day, S_a3Delay after shutdown T_SW/2, turn off S_a4；

S_a4Delay DP7 after turn-off, turn on S_a3；

S_a3Delay DP8 after switching on, turn off S_a2；

Off S_a2Delay DP9, turn on S_a1；

The working mode and the switching time interval when the load current is negative are:

the circuit is in a steady state, S₁、S_a1、S_a3In the on state, S₂、S_a2、S_a4In an off state; current conversion diode D_N1、D_N2Freewheel diode D_x1、D_x2A voltage stabilizing diode D_z1、D_z2And the anti-parallel diode of the switching tube is in a turn-off state;

t₀at time, turn off S_a3；

S_a3The delay DN1 after the shutdown is reached,conducting S_a4；

S_a4DN2 is delayed after conduction and S is turned off₁；

S₁Delay DP3 after shutdown, turn off S_a1；

S_a1Delay DP4 after turn-off, turn on S_a2；

S_a2Delay DP5 after conduction, turn on S₂；

S₂Delay after conduction T_onTurn off S₂；

S₂Delay DP6 after turn-off, turn on S₁；

At t₀Time of day, S_a3Delay after shutdown T_SW/2, turn off S_a4；

S_a4DN7 is delayed after the switch-off, and S is conducted_a3；

S_a3DN8 is delayed after conduction and S is turned off_a2；

Turning off Sa2, delaying DN9, and turning on Sa 1;

wherein the following parameters are input quantities: v_DCIs a dc bus voltage; v_AUXIs the auxiliary supply voltage; t is_{1A_min}The shortest ZVS on-time for Sa 4; t is_3BShortest on time of S1 (S2); i is_rThe part of the commutation current peak value exceeding the load current; c_{m_oss}Is a main switch tube S₁-S₂Parallel absorption capacitance: c_{m_oss}＝C₁＝C₂；C_{a_oss}For auxiliary switching of the tube S_a1-S_a4Parallel absorption capacitor C_{a_oss}＝C_a1＝C_a2＝C_a3＝C_a4(ii) a The following parameters can be expressed in terms of input quantity constraints; v_A'_UXIs the secondary side voltage of the transformer; l is_rIs a commutation inductance; l is_mIs an excitation inductor;

the exciting current value before the current conversion of the auxiliary switch is in positive correlation with the load current value in each switching period;

wherein T is_{13_min}To ignore the current change before charging the commutation current, i_LoadT obtained by adding 0₁-t₃The time interval of (c); t is_{1A_min}When the load current is 0, S_a4ZVS on time T_1AThe value of (c).

As a further improvement of the above scheme, the specific description of each mode and the calculation process of the interval time when the output current is positive are as follows:

mode 1 (t)<t₀): the circuit is in a steady state, S₂In a conducting state; load current I_LoadBy S₂Afterflow; s_a1、S_a3Conducting, exciting current i_LmBy S_a1、S_a3Free flow of value of

Mode 2 (t)₀-t₁)：t₀At time, turn off S_a3(ii) a Commutation inductor L_rThrough a transformer and an excitation inductor L_mAfter being connected in parallel with an auxiliary capacitor C_a3、C_a4Resonance occurs, the potential of the point R drops, and an equivalent circuit diagram is shown in FIG. 6; current converting inductive current

Increase from zero; excitation current

Changing to the positive direction;

this mode S_a3Voltage v across_Sa3And primary winding current

The expression is as follows:

exciting the inductive current according to the relation between the instantaneous value of the inductive current and the integral of the terminal voltage and the initial value of the current

And the current of the current converter

Wherein ω is_aFor resonant angular frequency:

at t₁Time of day, S_a3Voltage resonance at both ends to V_AUXThe time according to the present resonance mode is:

mode 3 (t)₁-t₂)：t₁At that time, the potential at the point R is reduced to 0, D_a4Natural conduction, S_a4Reaching ZVS commutation conditions, fig. 7 is an equivalent circuit diagram of this mode; the voltage at two ends of the exciting inductor is opposite to the current direction, and the magnitude of the exciting current is linearly reduced; the current of the commutation inductor is linearly increased; t is t_AAt that moment, the primary winding current is reduced to zero, S_a4May be in the time period t₁-t_AThe ZVS conduction is controlled between the two switches;

the primary winding current in the mode is as follows:

auxiliary pipe S_a4The soft on-time of (d) is:

S_a3turn off to S_a4The on-time interval DP1 is:

charging mode (t)₁-t₂) The current conversion inductance current is:

wherein: v'_AUXIs the secondary side voltage of the transformer;

t₂time of day, current of commutation

The value of (d) increases to a maximum value:

i_Lr(t₂)＝I_r+i_Load\ formula (33)

Wherein: i is_rFor converting current

Part of the load current is exceeded

Simultaneous, charging mode (T)_1-2) The duration of (c) is:

S_a4is conducted to S₂The off-time interval DP2 is:

mode 4 (t)₂-t₃):t₂At the moment, the main switch S₂Off, fig. 8 is an equivalent circuit diagram of this mode; current-converting inductive current i_LrPart I of the medium excess load current_rTo the capacitor C₁Discharge C₂Charging, and enabling the potential of the point O to start resonant rising;

potential v at point O_OAnd a current of commutation i_LrThe expression is as follows:

wherein:

t₃at that time, the potential at the point O rises to V_DC-V_A'_UX(ii) a The mode duration is:

wherein:

S₁is conducted to S_a1The off-time interval DP3 is:

DP3＝T_2-3formula (46)

Mode 5 (t)₃-t₅):t₃At that time, the potential at the point O rises to V_DC-V_A'_UXTurn off S_a1Excitation current i_LmIs increased to

Excitation current

To C_a1Charging C_a2Discharging, and enabling the potential of the point Q to start to approximately linearly decrease; t is t₄At that time, the potential at the point Q is lowered to 0, D_a2Conducting naturally;

t₃-t₄the duration is:

S_a1turn off to S_a2The on-time interval DP4 is:

DP4＝T_3-4formula (42)

Mode 6 (t)₅-t₆) At t₅Time of day, D₁Natural conduction, S₁The ZVS commutation condition is met; current-converting inductive current i_LrLinear decrease, t_BAt the moment, the current changes the inductive current i_LrDown to the load current i_Load(ii) a Main switch tube S₁May be in the time period t₅-t_BThe ZVS conduction is realized by controlling the conduction;

t₅at that time, the potential at the point O rises to V_DC；S₁The commutation time is as follows:

thus, obtaining: s₁ZVS on mode duration is:

S_a2is conducted to S₁The on-time interval DP5 is:

mode 7 (t)₆-t₈):t_B-t₆Determined by PWM control requirement, t₆At time, turn off S₁Load current i_LoadTo C₁Charging, C₂Discharging, and linearly reducing the potential of the O point; t is t₇At that time, the potential at the point O is reduced to 0, and the diode D₂Conducting naturally; s₂Can be at t₇Then controlling the conduction;

t₆-t₇the duration is:

S₁turn off to S₂The on-time interval DP6 is:

DP6＝T_6-7\ formula (48)

Mode 8 (t)₈-t₉):t₈At time, turn off S_a4FIG. 9 shows an equivalent circuit diagram of this mode, in which an excitation current is applied

To C_a4Charging C_a3Discharging, and the potential of the R point begins to rise;

potential v at point R_RAnd current

The expression is as follows:

wherein:

at t₉At the moment, the potential at the point R resonates to V_AUXThe pattern duration is:

mode 9 (t)₉-t₁₀):t₉At that time, the potential at the point R rises to V_AUX，D_a3Natural conduction, S_a3Reach ZVS commutation condition, t_CAt the moment, the excitation current is reduced to zero; s_a3May be in the time period T_9CControl conduction between the two;

the excitation current in the mode is as follows:

S_a3the soft on-time of (d) is:

S_a4turn off to S_a3The on-time interval DP7 is:

t₁₀time of day, exciting current

Is increased to

The mode duration is:

S_a3is conducted to S_a2The off-time interval DP8 is:

mode 10 (t)₁₀-t₁₁)：t₁₀At time, turn off S_a2(ii) a Auxiliary converter transformer excitation current

To C_a2Charging C_a1Discharging, and enabling the potential of the point Q to rise approximately linearly; t is t₁₁At that time, the potential at the point P rises to V_AUX，D_a1Conducting naturally; controlling conduction S before the next switching cycle_a1；

The mode duration is:

S_a2turn off to S_a1The on-time interval DP9 is:

DP9＝T_10-11formula (59)

The specific description of each mode and the calculation process of the interval time when the output current is negative are as follows:

mode 1 (t)<t₀): the circuit is in a steady state, S₁In a conducting state; load current I_LoadBy S₁Follow current, S_a1、S_a3Conducting, exciting current i_LmBy S_a1、S_a3Free flow of value of

Mode 2 (t)₀-t₁)：t₀At time, turn off S_a3(ii) a Commutation inductor L_rThrough a transformer and an excitation inductor L_mAfter being connected in parallel with an auxiliary capacitor C_a3、C_a4Resonance occurs, the potential of the point R drops, and an equivalent circuit diagram is shown in FIG. 6; current converting inductive current

Increase from zero; excitation current

Changing to the positive direction;

this mode S_a3Voltage v across_Sa3And primary winding current

The expression is as follows:

exciting the inductive current according to the relation between the instantaneous value of the inductive current and the integral of the terminal voltage and the initial value of the current

And the current of the current converter

Wherein ω is_aFor resonant angular frequency:

at t₁Time of day, S_a3Voltage resonance at both ends to V_AUXThe time according to the present resonance mode is:

mode 3 (t)₁-t₂)：t₁At that time, the potential at the point R is reduced to 0, D_a4Natural conduction, S_a4Reaching ZVS commutation condition, FIG. 7 is the equivalent circuit diagram of this mode; the voltage at two ends of the exciting inductor is opposite to the current direction, and the magnitude of the exciting current is linearly reduced; the current of the commutation inductor is linearly increased; t is t_AAt that moment, the primary winding current is reduced to zero, S_a4May be in the time period t₁-t_AThe ZVS conduction is controlled between the two switches;

the primary winding current in the mode is as follows:

auxiliary pipe S_a4The soft on-time of (d) is:

S_a3turn off to S_a4The on-time interval DN1 is: (ii) a

Charging mode (t)₁-t₂) The current conversion inductance current is:

wherein: v'_AUXIs the secondary side voltage of the transformer;

t₂time of day, current of commutation

The value of (d) increases to a maximum value:

i_Lr(t₂)＝I_r+i_Load\ formula (33)

Wherein: i is_rFor converting current

Part of the load current is exceeded

Simultaneous, charging mode (T)_1-2) The duration of (c) is:

S_a4is conducted to S₁The off-time interval DN2 is:

mode 4 (t)₂-t₃):t₂At the moment, the main switch S₁Off, fig. 8 is an equivalent circuit diagram of this mode;current-converting inductive current i_LrPart I of the medium excess load current_rTo the capacitor C₂Discharge C₁Charging, and the potential of the point O starts to decrease in resonance;

potential v at point O_OAnd a current of commutation i_LrThe expression is as follows:

wherein:

t₃at that time, the potential at point O is lowered to V'_AUX(ii) a The mode duration is:

wherein:

S₁is conducted to S_a1The off-time interval DN3 is:

DN3＝T_2-3formula (46)

Mode 5 (t)₃-t₅):t₃At that time, the potential at point O is lowered to V'_AUXTurn off S_a1Excitation current i_LmIs increased to

Excitation current

To C_a1Charging C_a2Discharging, and enabling the potential of the point Q to start to approximately linearly decrease; t is t₄At that time, the potential at the point Q is lowered to 0, D_a2Conducting naturally;

t₃-t₄the duration is:

S_a1turn off to S_a2The on-time interval DN4 is:

DN4＝T_3-4formula (42)

Mode 6 (t)₅-t₆) At t₅Time of day, D₂Natural conduction, S₂The ZVS commutation condition is met; current-converting inductive current i_LrLinear decrease, t_BAt the moment, the current changes the inductive current i_LrDown to the load current i_Load(ii) a Main switch tube S₂May be in the time period t₅-t_BThe ZVS conduction is realized by controlling the conduction;

t₅at that time, the potential at the point O rises to V_DC；S₂The commutation time is as follows:

thus, obtaining: s₂ZVS on mode duration is:

S_a2is conducted to S₁The on-time interval DN5 is:

mode 7 (t)₆-t₈):t_B-t₆Determined by PWM control requirement, t₆At time, turn off S₂Load current i_LoadTo C₂Charging, C₁Discharging, and linearly increasing the potential of the O point; t is t₇At that time, the potential at the point O rises to V_DCDiode D₁Conducting naturally; s₁Can be at t₇Then controlling the conduction;

t₆-t₇the duration is:

S₁turn off to S₂The on-time interval DN6 is:

DN6＝T_6-7\ formula (48)

Mode 8 (t)₈-t₉):t₈At time, turn off S_a4FIG. 9 shows an equivalent circuit diagram of this mode, in which an excitation current is applied

To C_a4Charging C_a3Discharging, and the potential of the R point begins to rise;

potential v at point R_RAnd current

The expression is as follows:

wherein:

at t₉At the moment, the potential at the point R resonates to V_AUXWhen this mode continuesThe method comprises the following steps:

mode 9 (t)₉-t₁₀):t₉At that time, the potential at the point R rises to V_AUXD_a3Natural conduction, S_a3Reach ZVS commutation condition, t_CAt the moment, the excitation current is reduced to zero; s_a3May be in the time period T_9CControl conduction between the two;

the excitation current in the mode is as follows:

S_a3the soft on-time of (d) is:

S_a4turn off to S_a3The on-time interval DN7 is:

t₁₀time of day, exciting current

Is increased to

The mode duration is:

S_a3is conducted to S_a2The off-time interval DN8 is:

mode 10 (t)₁₀-t₁₁)：t₁₀At time, turn off S_a2(ii) a Auxiliary converter transformer excitation current

To C_a2Charging C_a1Discharging, and enabling the potential of the point Q to rise approximately linearly; t is t₁₁At that time, the potential at the point P rises to V_AUX，D_a1Conducting naturally; controlling conduction S before the next switching cycle_a1；

The mode duration is:

S_a2turn off to S_a1The on-time interval DN9 is:

DN9＝T_10-11formula (59).

As a further improvement of the above scheme, it can be known from the analysis of the above circuit structure and working principle that the main switch needs to design a commutation inductor, a transformer turn ratio and a switch parallel absorption capacitor to complete zero-voltage commutation; the auxiliary switch needs to design an excitation inductor to complete zero voltage commutation;

the above design of each element parameter will be completed as follows (analysis with output current as positive):

when V'_AUXLess than V_DCWhen/2, the S is cut off under the condition that the commutation current is larger than the load current by a certain value₂Ensuring that the switching tube reliably completes current conversion; and the turn-off loss of the main switch is proportional to the square of the channel current at the turn-off instant [8,13 ]]Thus S₂The turn-off loss of the main switch is approximately negligible (turn-off loss is less than 1/10) when the formula is satisfied:

wherein I_{Load_rms}Is the effective value of the load current;

during actual circuit operation, load current detection has errors, resulting in I_rError of (2), influence commutation time T_2-5And ZVT on-time T_5BAfter summation of the formula I_rDerivation is carried out as_rThe dead time of the main switch when the formula is met can be a fixed value;

simultaneous:

thus, obtaining:

wherein the value range of beta obtained by the solution of the sum is as follows:

to ensure reliable commutation of the lagging arm and S_a4Sufficient ZVS on-time, taken together, to obtain:

to ensure magnetizing current in commutation inductor L_rAfter the linear discharge phase (t ═ t)₄) And a resonant inductor L_rBefore the linear charging phase (t ═ t)₁) Equal in magnitude and opposite in direction (neglecting the change of magnetizing current in the resonant commutation stage of the hysteresis arm at the primary side):

wherein T is₁₃T is obtained by summing up different time patterns of load₁-t₃Of each switching cycle, thereby

Different; it can be seen from the sum that when the load current is 0,

and T_1AMinimum value, L calculated under this condition_mAccording to the condition that S is greater than 0 when any load current is_a4There is a requirement for enough ZVS on-time;

will i_LoadT is the sum of 0₁-t₃The time interval of (c):

T₁₃＝T_{13_min}formula (104)

Simultaneous:

wherein T is_{1A_min}When the load current is 0, S_a4ZVS on time T_1AThe value of (c).

The invention has the beneficial effects that:

compared with the prior art, the circuit of the invention utilizes the phase correlation method to keep the prior art, realizes the advantage of zero voltage switching-on of the main switch tube, reduces the switching loss of the main switch, and in addition, the auxiliary switch in the auxiliary loop also realizes the zero voltage switching-on through the energy storage in the excitation inductor and the voltage withstanding value of the auxiliary switch is far smaller than that of the main switch; the magnetizing current reset is reliably realized in each switching period, and the volume of the transformer is effectively reduced; the secondary winding of the transformer is coupled to solve the problem of an auxiliary converter diode D_N1And D_N2The problem of overpressure.

Drawings

The following detailed description of embodiments of the invention is provided in conjunction with the appended drawings, in which:

FIG. 1 is a prior art [12] soft switching inverter circuit with an auxiliary loop using two transformers;

FIG. 2 is a prior art [11] soft switching inverter circuit with two transformers for the auxiliary loop;

FIG. 3 is an auxiliary resonant commutating pole inverter circuit with bi-directional reset of the phase-correlated magnetizing current of the present invention;

FIG. 4 is a first commutating diode (D)_C1) A freewheeling path for reverse recovery current;

FIG. 5 is a second commutating diode (D)_C2) A freewheeling path for reverse recovery current;

FIG. 6 is a state diagram of the circuit of the present invention for each mode of a PWM switching cycle when the output current is positive;

FIG. 7 is a state diagram of the circuit of the present invention in each mode during a PWM switching cycle when the output current is negative;

FIG. 8 is a schematic diagram of the equivalent circuit of mode 2 in one PWM switching cycle in accordance with the present invention;

FIG. 9 is a schematic diagram of the equivalent circuit of mode 3 in one PWM switching cycle according to the present invention;

FIG. 10 is a schematic diagram of the equivalent circuit of mode 4 in one PWM switching cycle according to the present invention;

FIG. 11 is a schematic diagram of the equivalent circuit of mode 8 in one PWM switching cycle according to the present invention;

FIG. 12 is a waveform diagram of the driving pulse signal and the main node voltage and the branch current of each switching tube in a PWM switching period when the output current is positive in the circuit of the present invention;

FIG. 13 is a waveform diagram of the driving pulse signal and the primary node voltage and current of each switching tube in a PWM switching period when the output current is negative.

Detailed Description

As shown in fig. 1-13, the auxiliary resonant inverter with symmetrically reset phase-related magnetizing currents provided by the present invention includes a first main switch transistor S1A second main switching tube S2, a first converter diode Dc1, a second converter diode Dc2, a first freewheeling diode Dx1, a second freewheeling diode Dx2, a direct-current power supply VDC, an auxiliary power supply VAUX, a Load first voltage-dividing capacitor Cd1, a second voltage-dividing capacitor Cd2, a resonant inductor Lr1, a resonant inductor Lr2, an auxiliary converter transformer primary winding T1, an auxiliary converter transformer secondary winding T2, an auxiliary converter transformer secondary winding T3, a first auxiliary switching tube Sa1, a second auxiliary switching tube Sa2, a third auxiliary switching tube Sa3, a fourth auxiliary switching tube Sa4, an AC-Lag lagging bridge arm AC-Lead exciting inductor Lm, wherein 1. the source electrode of the first main switching tube S1 and the drain electrode of the second main switching tube S2 are at an O point, and the two switching tubes are connected to form a main switching arm; the drain electrode of the first main switching tube S1, the cathode of the first commutation diode Dc1 and the cathode of the second freewheeling diode Dx2 are connected with the anode of the direct-current power supply VDC; the negative electrode of the direct-current power supply VDC is connected with the source electrode of the second main switching tube S2, the positive electrode of the second commutation diode Dc2 and the positive electrode of the first freewheeling diode Dx 1; one end of the Load is connected with the point O of the middle point of the bridge arm of the main switch, and the other end of the Load is connected with the middle points of the first voltage-dividing capacitor Cd1 and the second voltage-dividing capacitor Cd 2; one end of the resonant inductor Lr1 is connected with the point O of the midpoint of the main switch bridge arm, and the other end of the resonant inductor Lr1 is connected with the synonym end of the auxiliary side first winding T2 of the auxiliary converter transformer; the dotted terminal of the auxiliary side first winding T2 of the auxiliary converter transformer is connected with the anode of the first converter diode Dc1 and the cathode of the first freewheeling diode Dx 1; one end of the resonant inductor Lr2 is connected with the point O of the midpoint of the main switch bridge arm, and the other end of the resonant inductor Lr2 is connected with the synonym end of the secondary side second winding T3 of the auxiliary converter transformer; the dotted terminal of the secondary side second winding T3 of the auxiliary converter transformer is connected with the cathode of the second converter diode Dc2 and the anode of the second freewheeling diode Dx 2; the source electrode of the first auxiliary switching tube Sa1 and the drain electrode of the second auxiliary switching tube Sa2 are connected to a point Q, and the two switching tubes form an advance bridge arm AC-Lang of the commutation auxiliary circuit; the source electrode of the third auxiliary switching tube Sa3 and the drain electrode of the fourth auxiliary switching tube Sa4 are connected to a point R, and the two switching tubes form a hysteresis bridge arm AC-Lead of the commutation auxiliary circuit; the drain of the first auxiliary switch tube Sa1 and the drain of the third auxiliary switch tube Sa3 are connected to the positive electrode of the auxiliary power supply VAUX, the negative electrode of the auxiliary power supply VAUX is connected to the source electrode of the second auxiliary switch tube Sa2,the source electrode of the fourth auxiliary switching tube Sa4 is connected; the dotted end of the primary winding T1 of the auxiliary converter transformer is connected with the midpoint Q point of the leading auxiliary switch bridge arm, and the unlike end is connected with the midpoint R point of the lagging auxiliary switch bridge arm; the exciting inductance Lm is connected in parallel with two ends of a primary winding T1 of the auxiliary converter transformer; the number of turns of the first winding T2 and the second winding T3 on the secondary side of the auxiliary converter transformer is the same, the number of turns of the primary winding T1 of the auxiliary converter transformer and the turn ratio of T2 or T3 are 1/n, and the first freewheeling diode D_x1And a second freewheeling diode D_x2Has the effect of being at the first commutation diode D_c1And a second commutation diode D_c2Providing follow current paths for reverse current in reverse recovery process, wherein the follow current paths are respectively T₂->L_r1->S₂->D_X1->T₂And T₃->D_X2->S₁->L_r2->T₃。

As a further improvement of the above scheme, when the load current is positive, the operation mode and the switching time interval are as follows:

the circuit is in a steady state, S₂、S_a1、S_a3In the on state, S₁、S_a2、S_a4In an off state; current conversion diode D_N1、D_N2Freewheel diode D_x1、D_x2A voltage stabilizing diode D_z1、D_z2And the anti-parallel diode of the switching tube is in a turn-off state;

t₀at time, turn off S_a3；

S_a3Delay DP1 after turn-off, turn on S_a4；

S_a4Delay DP2 after switching on, turn off S₂；

S₂Delay DP3 after shutdown, turn off S_a1；

S_a1Delay DP4 after turn-off, turn on S_a2；

S_a2Delay DP5 after conduction, turn on S₁；

S₁Delay after conduction T_onTurn off S₁；

S₁Delay DP6 after turn-off, turn on S₂；

At t₀Time of day, S_a3Delay after shutdown T_SW/2, turn off S_a4；

S_a4Delay DP7 after turn-off, turn on S_a3；

S_a3Delay DP8 after switching on, turn off S_a2；

Off S_a2Delay DP9, turn on S_a1；

The working mode and the switching time interval when the load current is negative are:

the circuit is in a steady state, S₁、S_a1、S_a3In the on state, S₂、S_a2、S_a4In an off state; current conversion diode D_N1、D_N2Freewheel diode D_x1、D_x2A voltage stabilizing diode D_z1、D_z2And the anti-parallel diode of the switching tube is in a turn-off state;

t₀at time, turn off S_a3；

S_a3DN1 is delayed after the switch-off, and S is conducted_a4；

S_a4DN2 is delayed after conduction and S is turned off₁；

S₁Delay DP3 after shutdown, turn off S_a1；

S_a1Delay DP4 after turn-off, turn on S_a2；

S_a2Delay DP5 after conduction, turn on S₂；

S₂Delay after conduction T_onTurn off S₂；

S₂Delay DP6 after turn-off, turn on S₁；

At t₀Time of day, S_a3Delay after shutdown T_SW/2, turn off S_a4；

S_a4DN7 is delayed after the switch-off, and S is conducted_a3；

S_a3DN8 is delayed after conduction and S is turned off_a2；

Turning off Sa2, delaying DN9, and turning on Sa 1;

wherein the following parameters are input quantities: v_DCIs a dc bus voltage; v_AUXIs the auxiliary supply voltage; t is_{1A_min}The shortest ZVS on-time for Sa 4; t is_3BShortest on time of S1 (S2); i is_rThe part of the commutation current peak value exceeding the load current; c_{m_oss}Is a main switch tube S₁-S₂Parallel absorption capacitance: c_{m_oss}＝C₁＝C₂；C_{a_oss}For auxiliary switching of the tube S_a1-S_a4Parallel absorption capacitor C_{a_oss}＝C_a1＝C_a2＝C_a3＝C_a4(ii) a The following parameters can be expressed in terms of input quantity constraints; v_A'_UXIs the secondary side voltage of the transformer; l is_rIs a commutation inductance; l is_mIs an excitation inductor;

the exciting current value before the current conversion of the auxiliary switch is in positive correlation with the load current value in each switching period;

wherein T is_{13_min}To ignore the current change before charging the commutation current, i_LoadT obtained by adding 0₁-t₃The time interval of (c); t is_{1A_min}When the load current is 0, S_a4ZVS on time T_1AThe value of (c).

As a further improvement of the above scheme, the specific description of each mode and the calculation process of the interval time when the output current is positive are as follows:

mode 1 (t)<t₀): the circuit is in a steady state, S₂In a conducting state; load current I_LoadBy S₂Afterflow; s_a1、S_a3Conducting, exciting current i_LmBy S_a1、S_a3Free flow of value of

Mode 2 (t)₀-t₁)：t₀At time, turn off S_a3(ii) a Commutation inductor L_rThrough a transformer and an excitation inductor L_mAfter being connected in parallel with an auxiliary capacitor C_a3、C_a4Resonance occurs, the potential of the point R drops, and an equivalent circuit diagram is shown in FIG. 6; current converting inductive current

Increase from zero; excitation current

Changing to the positive direction;

this mode S_a3Voltage v across_Sa3And primary winding current

The expression is as follows:

exciting the inductive current according to the relation between the instantaneous value of the inductive current and the integral of the terminal voltage and the initial value of the current

And the current of the current converter

Wherein ω is_aFor resonant angular frequency:

at t₁Time of day, S_a3Voltage resonance at both ends to V_AUXThe time according to the present resonance mode is:

mode 3 (t)₁-t₂)：t₁At that time, the potential at the point R is reduced to 0, D_a4Natural conduction, S_a4Reaching ZVS commutation conditions, fig. 7 is an equivalent circuit diagram of this mode; the voltage at two ends of the exciting inductor is opposite to the current direction, and the magnitude of the exciting current is linearly reduced; the current of the commutation inductor is linearly increased; t is t_AAt that moment, the primary winding current is reduced to zero, S_a4May be in the time period t₁-t_AThe ZVS conduction is controlled between the two switches;

the primary winding current in the mode is as follows:

auxiliary pipe S_a4The soft on-time of (d) is:

S_a3turn off to S_a4The on-time interval DP1 is:

charging mode (t)₁-t₂) The current conversion inductance current is:

wherein: v'_AUXIs the secondary side voltage of the transformer;

t₂time of day, current of commutation

The value of (d) increases to a maximum value:

i_Lr(t₂)＝I_r+i_Load\ formula (33)

Wherein: i is_rFor converting current

Part of the load current is exceeded

Simultaneous, charging mode (T)_1-2) The duration of (c) is:

S_a4is conducted to S₂The off-time interval DP2 is:

mode 4 (t)₂-t₃):t₂At the moment, the main switch S₂Off, fig. 8 is an equivalent circuit diagram of this mode; current-converting inductive current i_LrPart I of the medium excess load current_rTo the capacitor C₁Discharge C₂Charging, and enabling the potential of the point O to start resonant rising;

potential v at point O_OAnd a current of commutation i_LrThe expression is as follows:

wherein:

t₃at that time, the potential at the point O rises to V_DC-V'_AUX(ii) a The mode duration is:

wherein:

S₁is conducted to S_a1The off-time interval DP3 is:

DP3＝T_2-3formula (46)

Mode 5 (t)₃-t₅):t₃At that time, the potential at the point O rises to V_DC-V'_AUXTurn off S_a1Excitation current i_LmIs increased to

Excitation current

To C_a1Charging C_a2Discharging, and enabling the potential of the point Q to start to approximately linearly decrease; t is t₄At that time, the potential at the point Q is lowered to 0, D_a2Conducting naturally;

t₃-t₄the duration is:

S_a1turn off to S_a2The on-time interval DP4 is:

DP4＝T_3-4formula (42)

Mode 6 (t)₅-t₆) At t₅Time of day, D₁Natural conduction, S₁The ZVS commutation condition is met; current-converting inductive current i_LrLinear decrease, t_BAt the moment, the current changes the inductive current i_LrDown to the load current i_Load(ii) a Main switch tube S₁May be in the time period t₅-t_BThe ZVS conduction is realized by controlling the conduction;

t₅at that time, the potential at the point O rises to V_DC；S₁The commutation time is as follows:

thus, obtaining: s₁ZVS on mode duration is:

S_a2is conducted to S₁The on-time interval DP5 is:

mode 7 (t)₆-t₈):t_B-t₆Determined by PWM control requirement, t₆At time, turn off S₁Load current i_LoadTo C₁Charging, C₂Discharging, and linearly reducing the potential of the O point; t is t₇At that time, the potential at the point O is reduced to 0, and the diode D₂Conducting naturally; s₂Can be at t₇Then controlling the conduction;

t₆-t₇the duration is:

S₁turn off to S₂The on-time interval DP6 is:

DP6＝T_6-7\ formula (48)

Mode 8 (t)₈-t₉):t₈At time, turn off S_a4FIG. 9 shows an equivalent circuit diagram of this mode, in which an excitation current is applied

To C_a4Charging C_a3Discharging, and the potential of the R point begins to rise;

potential v at point R_RAnd current

The expression is as follows:

wherein:

at t₉At the moment, the potential at the point R resonates to V_AUXThe pattern duration is:

mode 9 (t)₉-t₁₀):t₉At that time, the potential at the point R rises to V_AUX，D_a3Natural conduction, S_a3To reach ZVS commutation condition, t_CAt the moment, the excitation current is reduced to zero; s_a3May be in the time period T_9CControl conduction between the two;

the excitation current in the mode is as follows:

S_a3the soft on-time of (d) is:

S_a4turn off to S_a3The on-time interval DP7 is:

t₁₀time of day, exciting current

Is increased to

The mode duration is:

S_a3is conducted to S_a2The off-time interval DP8 is:

mode 10 (t)₁₀-t₁₁)：t₁₀At time, turn off S_a2(ii) a Auxiliary converter transformer excitation current

To C_a2Charging C_a1Discharging, and enabling the potential of the point Q to rise approximately linearly; t is t₁₁At that time, the potential at the point P rises to V_AUX，D_a1Conducting naturally; controlling conduction S before the next switching cycle_a1；

The mode duration is:

S_a2turn off to S_a1The on-time interval DP9 is:

DP9＝T_10-11formula (59)

The specific description of each mode and the calculation process of the interval time when the output current is negative are as follows:

mode 1 (t)<t₀): the circuit is in a steady state, S₁In a conducting state; load current I_LoadBy S₁Follow current, S_a1、S_a3Conducting, exciting current i_LmBy S_a1、S_a3Free flow of value of

Mode 2 (t)₀-t₁)：t₀At time, turn off S_a3(ii) a Commutation inductor L_rThrough a transformer and an excitation inductor L_mAfter being connected in parallel with an auxiliary capacitor C_a3、C_a4Resonance occurs, the potential of the point R drops, and an equivalent circuit diagram is shown in FIG. 6; current converting inductive current

Increase from zero; excitation current

Changing to the positive direction;

this mode S_a3Voltage v across_Sa3And primary winding current

The expression is as follows:

exciting the inductive current according to the relation between the instantaneous value of the inductive current and the integral of the terminal voltage and the initial value of the current

And the current of the current converter

Wherein ω is_aFor resonant angular frequency:

at t₁Time of day, S_a3Voltage resonance at both ends to V_AUXThe time according to the present resonance mode is:

mode 3 (t)₁-t₂)：t₁At that time, the potential at the point R is reduced to 0, D_a4Natural conduction, S_a4To achieveZVS commutation condition, FIG. 7 is the equivalent circuit diagram of this mode; the voltage at two ends of the exciting inductor is opposite to the current direction, and the magnitude of the exciting current is linearly reduced; the current of the commutation inductor is linearly increased; t is t_AAt that moment, the primary winding current is reduced to zero, S_a4May be in the time period t₁-t_AThe ZVS conduction is controlled between the two switches;

the primary winding current in the mode is as follows:

auxiliary pipe S_a4The soft on-time of (d) is:

S_a3turn off to S_a4The on-time interval DN1 is: (ii) a

Charging mode (t)₁-t₂) The current conversion inductance current is:

wherein: v'_AUXIs the secondary side voltage of the transformer;

t₂time of day, current of commutation

The value of (d) increases to a maximum value:

i_Lr(t₂)＝I_r+i_Load\ formula (33)

Wherein: i is_rFor converting current

Part of the load current is exceeded

Simultaneous, charging mode (T)_1-2) The duration of (c) is:

S_a4is conducted to S₁The off-time interval DN2 is:

mode 4 (t)₂-t₃):t₂At the moment, the main switch S₁Off, fig. 8 is an equivalent circuit diagram of this mode; current-converting inductive current i_LrPart I of the medium excess load current_rTo the capacitor C₂Discharge C₁Charging, and the potential of the point O starts to decrease in resonance;

potential v at point O_OAnd a current of commutation i_LrThe expression is as follows:

wherein:

t₃at that time, the potential at point O is lowered to V'_AUX(ii) a The mode duration is:

wherein:

S₁is conducted to S_a1The off-time interval DN3 is:

DN3＝T_2-3formula (46)

Mode 5 (t)₃-t₅):t₃At that time, the potential at point O is lowered to V'_AUXTurn off S_a1Excitation current i_LmIs increased to

Excitation current

To C_a1Charging C_a2Discharging, and enabling the potential of the point Q to start to approximately linearly decrease; t is t₄At that time, the potential at the point Q is lowered to 0, D_a2Conducting naturally;

t₃-t₄the duration is:

S_a1turn off to S_a2The on-time interval DN4 is:

DN4＝T_3-4formula (42)

Mode 6 (t)₅-t₆) At t₅Time of day, D₂Natural conduction, S₂The ZVS commutation condition is met; current-converting inductive current i_LrLinear decrease, t_BAt the moment, the current changes the inductive current i_LrDown to the load current i_Load(ii) a Main switch tube S₂May be in the time period t₅-t_BThe ZVS conduction is realized by controlling the conduction;

t₅at that time, the potential at the point O rises to V_DC；S₂The commutation time is as follows:

thus, obtaining: s₂ZVS on mode duration is:

S_a2is conducted to S₁The on-time interval DN5 is:

mode 7 (t)₆-t₈):t_B-t₆Determined by PWM control requirement, t₆At time, turn off S₂Load current i_LoadTo C₂Charging, C₁Discharging, and linearly increasing the potential of the O point; t is t₇At that time, the potential at the point O rises to V_DCDiode D₁Conducting naturally; s₁Can be at t₇Then controlling the conduction;

t₆-t₇the duration is:

S₁turn off to S₂The on-time interval DN6 is:

DN6＝T_6-7\ formula (48)

Mode 8 (t)₈-t₉):t₈At time, turn off S_a4FIG. 9 shows an equivalent circuit diagram of this mode, in which an excitation current is applied

To C_a4Charging C_a3Discharging, and the potential of the R point begins to rise;

potential v at point R_RAnd current

The expression is as follows:

wherein:

at t₉At the moment, the potential at the point R resonates to V_AUXThe pattern duration is:

mode 9 (t)₉-t₁₀):t₉At that time, the potential at the point R rises to V_AUXD_a3Natural conduction, S_a3Reach ZVS commutation condition, t_CAt the moment, the excitation current is reduced to zero; s_a3May be in the time period T_9CControl conduction between the two;

the excitation current in the mode is as follows:

S_a3the soft on-time of (d) is:

S_a4turn off to S_a3The on-time interval DN7 is:

t₁₀time of day, exciting current

Is increased to

The mode duration is:

S_a3is conducted to S_a2The off-time interval DN8 is:

mode 10 (t)₁₀-t₁₁)：t₁₀At time, turn off S_a2(ii) a Auxiliary converter transformer excitation current

To C_a2Charging C_a1Discharging, and enabling the potential of the point Q to rise approximately linearly; t is t₁₁At that time, the potential at the point P rises to V_AUX，D_a1Conducting naturally; controlling conduction S before the next switching cycle_a1；

The mode duration is:

S_a2turn off to S_a1The on-time interval DN9 is:

DN9＝T_10-11formula (59).

As a further improvement of the above scheme, it can be known from the analysis of the above circuit structure and working principle that the main switch needs to design a commutation inductor, a transformer turn ratio and a switch parallel absorption capacitor to complete zero-voltage commutation; the auxiliary switch needs to design an excitation inductor to complete zero voltage commutation;

the above design of each element parameter will be completed as follows (analysis with output current as positive):

when V'_AUXLess than V_DCWhen/2, the S is cut off under the condition that the commutation current is larger than the load current by a certain value₂Ensuring that the switching tube reliably completes current conversion; and the turn-off loss of the main switch is proportional to the square of the channel current at the turn-off instant [8,13 ]]Thus S₂The turn-off loss of the main switch is approximately negligible (turn-off loss is less than 1/10) when the formula is satisfied:

wherein I_{Load_rms}Is the effective value of the load current;

during actual circuit operation, load current detection has errors, resulting in I_rError of (2), influence commutation time T_2-5And ZVT on-time T_5BAfter summation of the formula I_rDerivation is carried out as_rThe dead time of the main switch when the formula is met can be a fixed value;

simultaneous:

thus, obtaining:

wherein the value range of beta obtained by the solution of the sum is as follows:

to ensure reliable commutation of the lagging arm and S_a4Sufficient ZVS on-time, taken together, to obtain:

to ensure magnetizing current in commutation inductor L_rAfter the linear discharge phase (t ═ t)₄) And a resonant inductor L_rBefore the linear charging phase (t ═ t)₁) Equal in magnitude and opposite in direction (neglecting the change of magnetizing current in the resonant commutation stage of the hysteresis arm at the primary side):

wherein T is₁₃T is obtained by summing up different time patterns of load₁-t₃Of each switching cycle, thereby

Different; it can be seen from the sum that when the load current is 0,

and T_1AMinimum value, L calculated under this condition_mAccording to the condition that S is greater than 0 when any load current is_a4There is a requirement for enough ZVS on-time;

will i_LoadT is the sum of 0₁-t₃The time interval of (c):

T₁₃＝T_{13_min}formula (104)

Simultaneous:

wherein T is_{1A_min}When the load current is 0, S_a4ZVS on time T_1AThe value of (c).

Auxiliary converter transformer T_XBy a primary winding T₁(number of winding turns N1), two secondary windings T₂、T₃Ideal transformer (N-2/N-1/N-3/N-1) and field inductance L (N-2, N-3 winding turns)_mComposition is carried out;

when the output current is positive, the state diagram of the circuit of each mode in one PWM switching period is shown in FIG. 4, and the waveforms of the driving pulse signal of each switching tube, the main node voltage and the branch current are shown in FIG. 10. When the output current is negative, the state diagram of the circuit in each mode in one PWM switching period is shown in fig. 5, and the waveforms of the driving pulse signal of each switching tube, the main node voltage and the branch current are shown in fig. 11.

The following analysis was performed for both cases where the output current was positive and negative, respectively. Since the load inductance is large enough, the load current is considered constant during one PWM switching period.

The forward direction of reference for each electrical variable in the loop coincides with the direction of the arrow in fig. 3.

The input parameters are shown in table 1:

input DC voltage (V)DC)	400V
		Auxiliary voltage (V)AUX)	20V
Switching frequency (f)sw)	20KHz
		Cm_oss	100pF
Ca_oss	1000pF
		Ir	2A
T1A	10ns
		T3B	10ns

TABLE 1 input parameters

Specific values of inductance and transformer calculated from constraints of input parameters are shown in Table 2

Commutation inductance (L)r)	4.21uH
		Excitation inductor (L)m)	954nH
Secondary side voltage (V) of transformerA'UX)	60V

TABLE 2

Each duration and

the relationship to load current is as follows:

DP3＝DN3＝T_2-323.5ns \ equation (109)

The above embodiments are not limited to the technical solutions of the embodiments themselves, and the embodiments may be combined with each other into a new embodiment. The above embodiments are only for illustrating the technical solutions of the present invention and are not limited thereto, and any modification or equivalent replacement without departing from the spirit and scope of the present invention should be covered within the technical solutions of the present invention.

Claims (4)

1. An auxiliary resonance converter pole inverter with phase-correlated magnetizing current symmetrical reset is characterized in that: the auxiliary converter transformer comprises a first main switching tube (S1), a second main switching tube (S2), a first converter diode (Dc1), a second converter diode (Dc2), a first freewheeling diode (Dx1), a second freewheeling diode (Dx2), a direct current power supply (VDC) auxiliary power supply (VAUX) Load (Load), a first voltage division capacitor (Cd1), a second voltage division capacitor (Cd2), a resonant inductor (Lr1), a resonant inductor (Lr2), an auxiliary converter transformer primary winding (T1), an auxiliary converter transformer secondary side first winding (T2), a second winding (T3) at the auxiliary converter secondary side, a second auxiliary switching tube (Sa1), a third auxiliary switching tube (Sa3), a fourth auxiliary switching tube (Sa4), a leading bridge arm (AC-Lag) lagging bridge arm (AC-Lm) exciting inductor (Sa4), a first main switching tube (S2), a second switching tube (S638), a second auxiliary switching tube (Cd1), the two switching tubes form a main switching bridge arm; the drain electrode of the first main switching tube (S1), the cathode of the first commutation diode (Dc1) and the cathode of the second freewheeling diode (Dx2) are connected with the anode of a direct-current power supply (VDC); the negative electrode of the direct current power supply (VDC) is connected with the source electrode of the second main switching tube (S2), the positive electrode of the second commutation diode (Dc2) and the positive electrode of the first freewheeling diode (Dx 1); one end of a Load (Load) is connected with a point O of the middle point of the bridge arm of the main switch, and the other end of the Load (Load) is connected with the middle points of a first voltage-dividing capacitor (Cd1) and a second voltage-dividing capacitor (Cd 2); one end of a resonant inductor (Lr1) is connected with the point O of the midpoint of the main switch bridge arm, and the other end of the resonant inductor is connected with the synonym end of the auxiliary side first winding (T2) of the auxiliary converter transformer; the dotted terminal of the auxiliary side first winding (T2) of the auxiliary converter transformer is connected with the anode of the first converter diode (Dc1) and the cathode of the first freewheeling diode (Dx 1); one end of the resonant inductor (Lr2) is connected with the point O of the midpoint of the main switch bridge arm, and the other end of the resonant inductor is connected with the synonym end of the secondary side second winding (T3) of the auxiliary converter transformer; secondary winding of auxiliary converter transformerThe dotted terminal of the group (T3) is connected with the cathode of the second commutation diode (Dc2) and the anode of the second freewheeling diode (Dx 2); the source electrode of the first auxiliary switching tube (Sa1) and the drain electrode of the second auxiliary switching tube (Sa2) are connected to a point Q, and the two switching tubes form a leading bridge arm (AC-Lang) of the commutation auxiliary circuit; the source electrode of the third auxiliary switching tube (Sa3) and the drain electrode of the fourth auxiliary switching tube (Sa4) are connected to the R point, and the two switching tubes form a hysteresis bridge arm (AC-Lead) of the commutation auxiliary circuit; the drain electrode of the first auxiliary switch tube (Sa1) and the drain electrode of the third auxiliary switch tube (Sa3) are connected with the positive electrode of the auxiliary power supply (VAUX), the negative electrode of the auxiliary power supply (VAUX) is connected with the source electrode of the second auxiliary switch tube (Sa2), and the source electrode of the fourth auxiliary switch tube (Sa 4); the dotted end of the primary winding (T1) of the auxiliary converter transformer is connected with the midpoint Q point of the leading auxiliary switch bridge arm, and the unlike end is connected with the midpoint R point of the lagging auxiliary switch bridge arm; the exciting inductance Lm is connected in parallel with two ends of a primary winding (T1) of the auxiliary converter transformer; the number of turns of a first winding (T2) and a second winding (T3) on the secondary side of the auxiliary converter transformer is the same, the number of turns of a primary winding (T1) of the auxiliary converter transformer and the turn ratio of T2 (or T3) are 1/n, and the first freewheeling diode (D)_x1) And a second freewheeling diode (D)_x2) Is applied to the first commutation diode (D)_c1) And a second commutation diode (D)_c2) Providing follow current paths for reverse current in reverse recovery process, wherein the follow current paths are respectively T₂->L_r1->S₂->D_X1->T₂And T₃->D_X2->S₁->L_r2->T₃。

2. A phase-correlated magnetizing current symmetrically reset auxiliary resonant commutating pole inverter of claim 1, characterized by:

when the load current is positive, the working mode and the switching time interval are as follows:

the circuit is in a steady state, S₂、S_a1、S_a3In the on state, S₁、S_a2、S_a4In an off state; current conversion diode D_N1、D_N2Freewheel diode D_x1、D_x2A voltage stabilizing diode D_z1、D_z2And the anti-parallel diode of the switching tube is in a turn-off state;

t₀at time, turn off S_a3；

S_a3Delay DP1 after turn-off, turn on S_a4；

S_a4Delay DP2 after switching on, turn off S₂；

S₂Delay DP3 after shutdown, turn off S_a1；

S_a1Delay DP4 after turn-off, turn on S_a2；

S_a2Delay DP5 after conduction, turn on S₁；

S₁Delay after conduction T_onTurn off S₁；

S₁Delay DP6 after turn-off, turn on S₂；

At t₀Time of day, S_a3Delay after shutdown T_SW/2, turn off S_a4；

S_a4Delay DP7 after turn-off, turn on S_a3；

S_a3Delay DP8 after switching on, turn off S_a2；

Off S_a2Delay DP9, turn on S_a1；

The working mode and the switching time interval when the load current is negative are:

the circuit is in a steady state, S₁、S_a1、S_a3In the on state, S₂、S_a2、S_a4In an off state; current conversion diode D_N1、D_N2Freewheel diode D_x1、D_x2A voltage stabilizing diode D_z1、D_z2And the anti-parallel diode of the switching tube is in a turn-off state;

t₀at time, turn off S_a3；

S_a3DN1 is delayed after the switch-off, and S is conducted_a4；

S_a4DN2 is delayed after conduction and S is turned off₁；

S₁Delay DP3 after shutdown, turn off S_a1；

S_a1Delay DP4 after turn-off, turn on S_a2；

S_a2Delay DP5 after conduction, turn on S₂；

S₂Delay after conduction T_onTurn off S₂；

S₂Delay DP6 after turn-off, turn on S₁；

At t₀Time of day, S_a3Delay after shutdown T_SW/2, turn off S_a4；

S_a4DN7 is delayed after the switch-off, and S is conducted_a3；

S_a3DN8 is delayed after conduction and S is turned off_a2；

Turning off Sa2, delaying DN9, and turning on Sa 1;

wherein the following parameters are input quantities: v_DCIs a dc bus voltage; v_AUXIs the auxiliary supply voltage; t is_{1A_min}The shortest ZVS on-time for Sa 4; t is_3BShortest on time of S1 (S2); i is_rThe part of the commutation current peak value exceeding the load current; c_{m_oss}Is a main switch tube S₁-S₂Parallel absorption capacitance: c_{m_oss}＝C₁＝C₂；C_{a_oss}For auxiliary switching of the tube S_a1-S_a4Parallel absorption capacitor C_{a_oss}＝C_a1＝C_a2＝C_a3＝C_a4(ii) a The following parameters can be expressed in terms of input quantity constraints; v'_AUXIs the secondary side voltage of the transformer; l is_rIs a commutation inductance; l is_mIs an excitation inductor;

the exciting current value before the current conversion of the auxiliary switch is in positive correlation with the load current value in each switching period;

wherein T is_{13_min}To ignore the current change before charging the commutation current, i_LoadT obtained by adding 0₁-t₃The time interval of (c); t is_{1A_min}When the load current is 0, S_a4ZVS on time T_1AThe value of (c).

3. A phase-correlated magnetizing current symmetrically reset auxiliary resonant commutating pole inverter of claim 2, characterized by:

the specific description of each mode and the calculation process of the interval time when the output current is positive are as follows:

mode 1 (t)<t₀): the circuit is in a steady state, S₂In a conducting state; load current I_LoadBy S₂Afterflow; s_a1、S_a3Conducting, exciting current i_LmBy S_a1、S_a3Free flow of value of

Mode 2 (t)₀-t₁)：t₀At time, turn off S_a3(ii) a Commutation inductor L_rThrough a transformer and an excitation inductor L_mAfter being connected in parallel with an auxiliary capacitor C_a3、C_a4Resonance occurs, the potential of the point R drops, and an equivalent circuit diagram is shown in FIG. 6; current converting inductive current

Increase from zero; excitation current

Changing to the positive direction;

this mode S_a3Voltage v across_Sa3And primary winding current

The expression is as follows:

exciting the inductive current according to the relation between the instantaneous value of the inductive current and the integral of the terminal voltage and the initial value of the current

And the current of the current converter

Wherein ω is_aFor resonant angular frequency:

at t₁Time of day, S_a3Voltage resonance at both ends to V_AUXThe time according to the present resonance mode is:

mode 3 (t)₁-t₂)：t₁At that time, the potential at the point R is reduced to 0, D_a4Natural conduction, S_a4Reaching ZVS commutation conditions, fig. 7 is an equivalent circuit diagram of this mode; the voltage at two ends of the exciting inductor is opposite to the current direction, and the magnitude of the exciting current is linearly reduced; the current of the commutation inductor is linearly increased; t is t_AAt that moment, the primary winding current is reduced to zero, S_a4May be in the time period t₁-t_AThe ZVS conduction is controlled between the two switches;

the primary winding current in the mode is as follows:

auxiliary pipe S_a4The soft on-time of (d) is:

S_a3turn off to S_a4The on-time interval DP1 is:

charging mode (t)₁-t₂) The current conversion inductance current is:

wherein: v'_AUXIs the secondary side voltage of the transformer;

t₂time of day, current of commutation

The value of (d) increases to a maximum value:

i_Lr(t₂)＝I_r+i_Load\ formula (33)

Wherein: i is_rFor converting current

Part of the load current is exceeded

Simultaneous, charging mode (T)_1-2) The duration of (c) is:

S_a4is conducted to S₂The off-time interval DP2 is:

mode 4 (t)₂-t₃):t₂At the moment, the main switch S₂Off, fig. 8 is an equivalent circuit diagram of this mode; current-converting inductive current i_LrPart I of the medium excess load current_rTo the capacitor C₁Discharge C₂Charging, and enabling the potential of the point O to start resonant rising;

potential v at point O_OAnd a current of commutation i_LrThe expression is as follows:

wherein:

t₃at that time, the potential at the point O rises to V_DC-V′_AUX(ii) a The mode duration is:

wherein:

S₁is conducted to S_a1The off-time interval DP3 is:

DP3＝T_2-3formula (46)

Mode 5 (t)₃-t₅):t₃At that time, the potential at the point O rises to V_DC-V′_AUXTurn off S_a1Excitation current i_LmIs increased to

Excitation current

To C_a1Charging C_a2Discharging, and enabling the potential of the point Q to start to approximately linearly decrease; t is t₄At that time, the potential at the point Q is lowered to 0, D_a2Conducting naturally;

t₃-t₄the duration is:

S_a1turn off to S_a2The on-time interval DP4 is:

DP4＝T_3-4formula (42)

Mode 6 (t)₅-t₆) At t₅Time of day, D₁The switch-on is carried out naturally,S₁the ZVS commutation condition is met; current-converting inductive current i_LrLinear decrease, t_BAt the moment, the current changes the inductive current i_LrDown to the load current i_Load(ii) a Main switch tube S₁May be in the time period t₅-t_BThe ZVS conduction is realized by controlling the conduction;

t₅at that time, the potential at the point O rises to V_DC；S₁The commutation time is as follows:

thus, obtaining: s₁ZVS on mode duration is:

S_a2is conducted to S₁The on-time interval DP5 is:

mode 7 (t)₆-t₈):t_B-t₆Determined by PWM control requirement, t₆At time, turn off S₁Load current i_LoadTo C₁Charging, C₂Discharging, and linearly reducing the potential of the O point; t is t₇At that time, the potential at the point O is reduced to 0, and the diode D₂Conducting naturally; s₂Can be at t₇Then controlling the conduction;

t₆-t₇the duration is:

S₁turn off to S₂The on-time interval DP6 is:

DP6＝T_6-7\ formula (48)

Mode 8 (t)₈-t₉):t₈At time, turn off S_a4FIG. 9 shows an equivalent circuit diagram of this mode, in which an excitation current is applied

To C_a4Charging C_a3Discharging, and the potential of the R point begins to rise;

potential v at point R_RAnd current

The expression is as follows:

wherein:

at t₉At the moment, the potential at the point R resonates to V_AUXThe pattern duration is:

mode 9 (t)₉-t₁₀):t₉At that time, the potential at the point R rises to V_AUX，D_a3Natural conduction, S_a3Reach ZVS commutation condition, t_CAt the moment, the excitation current is reduced to zero; s_a3May be in the time period T_9CControl conduction between the two;

the excitation current in the mode is as follows:

S_a3the soft on-time of (d) is:

S_a4turn off to S_a3The on-time interval DP7 is:

t₁₀time of day, exciting current

Is increased to

The mode duration is:

S_a3is conducted to S_a2The off-time interval DP8 is:

mode 10 (t)₁₀-t₁₁)：t₁₀At time, turn off S_a2(ii) a Auxiliary converter transformer excitation current

To C_a2Charging C_a1Discharge, potential approximation of Q-pointLinearly increasing; t is t₁₁At that time, the potential at the point P rises to V_AUX，D_a1Conducting naturally; controlling conduction S before the next switching cycle_a1；

The mode duration is:

S_a2turn off to S_a1The on-time interval DP9 is:

DP9＝T_10-11formula (59)

The specific description of each mode and the calculation process of the interval time when the output current is negative are as follows:

mode 1 (t)<t₀): the circuit is in a steady state, S₁In a conducting state; load current I_LoadBy S₁Follow current, S_a1、S_a3Conducting, exciting current i_LmBy S_a1、S_a3Free flow of value of

Mode 2 (t)₀-t₁)：t₀At time, turn off S_a3(ii) a Commutation inductor L_rThrough a transformer and an excitation inductor L_mAfter being connected in parallel with an auxiliary capacitor C_a3、C_a4Resonance occurs, the potential of the point R drops, and an equivalent circuit diagram is shown in FIG. 6; current converting inductive current

Increase from zero; excitation current

Changing to the positive direction;

this mode S_a3Voltage v across_Sa3And primary winding current

The expression is as follows:

exciting the inductive current according to the relation between the instantaneous value of the inductive current and the integral of the terminal voltage and the initial value of the current

And the current of the current converter

Wherein ω is_aFor resonant angular frequency:

at t₁Time of day, S_a3Voltage resonance at both ends to V_AUXThe time according to the present resonance mode is:

mode 3 (t)₁-t₂)：t₁At that time, the potential at the point R is reduced to 0, D_a4Natural conduction, S_a4Reaching ZVS commutation condition, FIG. 7 is the equivalent circuit diagram of this mode; the voltage at two ends of the exciting inductor is opposite to the current direction, and the magnitude of the exciting current is linearly reduced; the current of the commutation inductor is linearly increased; t is t_AAt that moment, the primary winding current is reduced to zero, S_a4May be in the time period t₁-t_AThe ZVS conduction is controlled between the two switches;

the primary winding current in the mode is as follows:

auxiliary pipe S_a4The soft on-time of (d) is:

S_a3turn off to S_a4The on-time interval DN1 is: (ii) a

Charging mode (t)₁-t₂) The current conversion inductance current is:

wherein: v'_AUXIs the secondary side voltage of the transformer;

t₂time of day, current of commutation

The value of (d) increases to a maximum value:

i_Lr(t₂)＝I_r+i_Load\ formula (33)

Wherein: i is_rFor converting current

Part of the load current is exceeded

Simultaneous, charging mode (T)_1-2) The duration of (c) is:

S_a4is conducted to S₁The off-time interval DN2 is:

mode 4 (t)₂-t₃):t₂At the moment, the main switch S₁Off, fig. 8 is an equivalent circuit diagram of this mode; current-converting inductive current i_LrPart I of the medium excess load current_rTo the capacitor C₂Discharge C₁Charging, and the potential of the point O starts to decrease in resonance;

potential v at point O_OAnd a current of commutation i_LrThe expression is as follows:

wherein:

t₃at that time, the potential at point O is lowered to V'_AUX(ii) a Book mouldThe duration of formula is:

wherein:

S₁is conducted to S_a1The off-time interval DN3 is:

DN3＝T_2-3formula (46)

Mode 5 (t)₃-t₅):t₃At that time, the potential at point O is lowered to V'_AUXTurn off S_a1Excitation current i_LmIs increased to

Excitation current

To C_a1Charging C_a2Discharging, and enabling the potential of the point Q to start to approximately linearly decrease; t is t₄At that time, the potential at the point Q is lowered to 0, D_a2Conducting naturally;

t₃-t₄the duration is:

S_a1turn off to S_a2The on-time interval DN4 is:

DN4＝T_3-4formula (42)

Mode 6 (t)₅-t₆) At t₅Time of day, D₂Natural conduction, S₂The ZVS commutation condition is met; current-converting inductive current i_LrLinear decrease, t_BAt the moment, the current changes the inductive current i_LrDown to the load current i_Load(ii) a Main switch tube S₂May be in the time period t₅-t_BThe ZVS conduction is realized by controlling the conduction;

t₅at that time, the potential at the point O rises to V_DC；S₂The commutation time is as follows:

thus, obtaining: s₂ZVS on mode duration is:

S_a2is conducted to S₁The on-time interval DN5 is:

mode 7 (t)₆-t₈):t_B-t₆Determined by PWM control requirement, t₆At time, turn off S₂Load current i_LoadTo C₂Charging, C₁Discharging, and linearly increasing the potential of the O point; t is t₇At that time, the potential at the point O rises to V_DCDiode D₁Conducting naturally; s₁Can be at t₇Then controlling the conduction;

t₆-t₇the duration is:

S₁turn off to S₂The on-time interval DN6 is:

DN6＝T_6-7\ formula (48)

Mode 8 (t)₈-t₉):t₈At time, turn off S_a4Book, bookThe equivalent circuit diagram of the mode is shown in FIG. 9, the exciting current

To C_a4Charging C_a3Discharging, and the potential of the R point begins to rise;

potential v at point R_RAnd current

The expression is as follows:

wherein:

at t₉At the moment, the potential at the point R resonates to V_AUXThe pattern duration is:

mode 9 (t)₉-t₁₀):t₉At that time, the potential at the point R rises to V_AUXD_a3Natural conduction, S_a3Reach ZVS commutation condition, t_CAt the moment, the excitation current is reduced to zero; s_a3May be in the time period T_9CControl conduction between the two;

the excitation current in the mode is as follows:

S_a3the soft on-time of (d) is:

S_a4turn off to S_a3The on-time interval DN7 is:

t₁₀time of day, exciting current

Is increased to

The mode duration is:

S_a3is conducted to S_a2The off-time interval DN8 is:

mode 10 (t)₁₀-t₁₁)：t₁₀At time, turn off S_a2(ii) a Auxiliary converter transformer excitation current

To C_a2Charging C_a1Discharging, and enabling the potential of the point Q to rise approximately linearly; t is t₁₁At that time, the potential at the point P rises to V_AUX，D_a1Conducting naturally; controlling conduction S before the next switching cycle_a1；

The mode duration is:

S_a2turn off to S_a1The on-time interval DN9 is:

DN9＝T_10-11formula (59).

4. A phase-correlated magnetizing current symmetrically reset auxiliary resonant commutating pole inverter of claim 3, characterized by: according to the analysis of the circuit structure and the working principle, the main switch needs to design a converter inductor, a transformer turn ratio and a switch parallel absorption capacitor when finishing zero voltage conversion; the auxiliary switch needs to design an excitation inductor to complete zero voltage commutation;

the above design of each element parameter will be completed as follows (analysis with output current as positive):

when V'_AUXLess than V_DCWhen/2, the S is cut off under the condition that the commutation current is larger than the load current by a certain value₂Ensuring that the switching tube reliably completes current conversion; and the turn-off loss of the main switch is proportional to the square of the channel current at the turn-off instant [8,13 ]]Thus S₂The turn-off loss of the main switch is approximately negligible (turn-off loss is less than 1/10) when the formula is satisfied:

wherein I_{Load_rms}Is the effective value of the load current;

during actual circuit operation, load current detection has errors, resulting in I_rError of (2), influence commutation time T_2-5And ZVT on-time T_5BAfter summation of the formula I_rDerivation is carried out as_rThe dead time of the main switch when the formula is met can be a fixed value;

simultaneous:

thus, obtaining:

wherein the value range of beta obtained by the solution of the sum is as follows:

to ensure reliable commutation of the lagging arm and S_a4Sufficient ZVS on-time, taken together, to obtain:

to ensure magnetizing current in commutation inductor L_rAfter the linear discharge phase (t ═ t)₄) And a resonant inductor L_rBefore the linear charging phase (t ═ t)₁) Equal in magnitude and opposite in direction (neglecting the change of magnetizing current in the resonant commutation stage of the hysteresis arm at the primary side):

wherein T is₁₃T is obtained by summing up different time patterns of load₁-t₃Of each switching cycle, thereby

Different; it can be seen from the sum that when the load current is 0,

and T_1AMinimum value, L calculated under this condition_mAccording to the condition that S is greater than 0 when any load current is_a4There is a requirement for enough ZVS on-time;

will i_LoadT is the sum of 0₁-t₃The time interval of (c):

T₁₃＝T_{13_min}formula (104)

Simultaneous:

wherein T is_{1A_min}When the load current is 0, S_a4ZVS on time T_1AThe value of (c).

Images