CN111478611A - An auxiliary resonant commutated pole inverter with bidirectional reset of phase-dependent magnetizing current - Google Patents

Abstract

The invention discloses an auxiliary resonant commutating pole inverter whose phase-related magnetizing current is bidirectionally reset, which realizes the advantages of zero-voltage turn-on of the main switch tube and reduces the switching loss of the main switch. It also realizes zero-voltage turn-on through the energy storage in the magnetizing inductance, and its withstand voltage value is much smaller than that of the main switch; and the magnetizing current reset is reliably realized in each switching cycle, which effectively reduces the volume of the transformer; the secondary side of the transformer The winding coupling solves the overvoltage problem of the auxiliary commutating diodes D _c1 and D _c2 . The zero-voltage turn-on of the main switch and the auxiliary switch can be realized; the efficiency and power density are effectively improved, and the cost and EMI are reduced.

Description

An auxiliary resonant commutated pole inverter with bidirectional reset of phase-dependent magnetizing current

technical field

The invention relates to the technical field of power electronic converters, in particular to an auxiliary resonant commutating pole inverter with phase-related magnetizing current bidirectional reset.

Background technique

Voltage Source Inverter (VSI), which is essentially a synchronous rectification buck-boost converter composed of a fully controlled switching half-bridge, is widely used in applications of various power levels, such as motor drives, active power Filters, uninterruptible power supplies (UPS), photovoltaic power systems, fuel cell power systems and distributed power grids, etc. The core of its research is to improve efficiency and power density.

Under hard switching conditions, power density is usually increased by increasing the switching frequency and reducing the size and weight of passive components such as filter inductors and capacitors, but increasing the switching frequency results in switching losses and high frequency electromagnetic interference (EMI). increase, thereby reducing the efficiency of the inverter. In VSI, the circuit is an inverter half-bridge and an inductor connected to the mid-point of the half-bridge; during hard switching, after the freewheeling mode, the energy Qrr stored in the anti-parallel diode and the output capacitor of the switch to be turned on at the moment of turning on, Qoss is released into the channel of the switch tube to generate peak current, turn-on loss and high-frequency electromagnetic interference (EMI). One way to overcome the above problems (switching losses and EMI) is the advancement of switching device technology, and the other is the soft-switching topology technology.

Compared with traditional Si power semiconductors, wide bandgap semiconductors such as SiC and GaN have faster turn-on and turn-off times, lower turn-off losses and lower parasitic capacitance; frequency electromagnetic interference (EMI). In addition, SiC has the problems of harsh gate turn-on and turn-off conditions and high cost.

Soft-switching topologies can reduce switching losses and EMI at high switching frequencies. The soft switching topology reduces switching losses by adding auxiliary circuits to decouple the transition edges of the current and voltage of the switch. In many soft-switching inverter topologies, the auxiliary resonant pole soft-switching inverter does not affect the normal operation of the main circuit because it does not increase the voltage and current stress of the switch tubes in the main loop and the auxiliary loop only works when the switch tubes are commutated. is generally recognized.

For the prior art, see the article "An Improved Zero-Voltage Switching Inverter Using Two CoupledMagnetics in One Resonant Pole" published in IEEE Transactions on Power Electronics, Vol. 25, No. 4, 2010. The double coupled inductor (ZVT-2CI) circuit can It realizes the zero-voltage turn-on of the main switch and the zero-current switch of the auxiliary switch and solves the problem that the excitation current cannot be reset. The commutator diode has no clamping measures. After the resonant current drops to 0, it will cause the DC bus voltage at both ends of the commutator diode to bear about twice the voltage, and it will cause the potential oscillation of the unclamped end of the diode; for the prior art, see IEEE 201315th European Conference on Power Electronics and Applications (EPE) New topology of three phase softswitching inverter using a dual auxiliary circuit, which can realize zero-voltage turn-on of the main switch and zero-current switch of the auxiliary switch to reset the magnetization by disconnecting the freewheeling path of the excitation current current. But diodes in series on high current loops will add additional losses. In the above two methods, one coupled inductor can only realize zero-voltage turn-on of one main switch tube, so two coupled inductors need to be used in one auxiliary circuit, thus increasing the volume, cost and leakage inductance loss of the transformer.

SUMMARY OF THE INVENTION

In order to solve the shortcomings and deficiencies of the prior art, the circuit of the present invention maintains the prior art by using the phase correlation method, realizes the zero-voltage turn-on of the main switch and the auxiliary switch, effectively improves the efficiency and power density, and reduces the cost and EMI.

To achieve the purpose of the present invention, an auxiliary resonant commutated pole inverter with bidirectional reset of phase-related magnetizing current is provided, comprising a first main switch tube (S ₁ ), a second main switch tube (S ₂ ), a first main switch tube (S 2 ), a first main switch tube (S 2 ), a first main switch tube (S 2 ), Commutation diode (D _c1 ), second commutation diode (D _c2 ), DC power supply (V _DC ), auxiliary power supply (V _AUX ), load (Load), magnetizing inductance (L _m ), first voltage dividing capacitor C _d1 , the second voltage dividing capacitor C _d2 , the resonant inductance (L _r ), the first winding (T ₂ ) on the secondary side of the auxiliary converter transformer, the second winding (T ₃ ) on the secondary side of the auxiliary converter transformer, and the first auxiliary switch tube (S _a1 ), the second auxiliary switch tube (S _a2 ), the third auxiliary switch tube (S _a3 ), the fourth auxiliary switch tube (S _a4 ), the lead bridge arm (AC-Lag), the lag bridge arm (AC- Lead); the source of the first main switch tube (S ₁ ) and the drain of the second main switch tube (S ₂ ) are connected to point O, and these two switch tubes constitute the main switch bridge arm; the first main switch The drain of the tube (S ₁ ) and the negative pole of the first commutation diode (D _c1 ) are connected to the positive pole of the DC power supply (V _DC ); the negative pole of the DC power supply (V _DC ) is connected to the negative pole of the second main switch tube (S ₂ ). The source is connected to the anode of the second commutation diode (D _c2 ); one end of the load (Load) is connected to the midpoint O point of the main switch bridge arm, and the other end is connected to the two first voltage dividing capacitors C _d1 and the second voltage dividing The midpoint of the capacitor C _d2 is connected; one end of the resonant inductance (L _r ) is connected to the midpoint O of the main switch bridge arm, and the other end is connected to the synonymous end of the first winding (T ₂ ) on the secondary side of the auxiliary converter transformer, the auxiliary The same name end of the second winding (T ₃ ) on the secondary side of the converter transformer is connected to point P; the same name end of the first winding (T ₂ ) on the secondary side of the auxiliary converter transformer is connected with the positive electrode of the first converter diode (D _c1 ); The synonym end of the second winding (T ₃ ) on the secondary side of the auxiliary converter transformer is connected to the negative electrode of the second converter diode (D _c2 ); the source of the first auxiliary switch tube (S _a1 ) is connected to the second auxiliary switch tube ( The drain of S _a2 ) is connected to point Q, and these two switches constitute the leading bridge arm (AC-Lag) of the commutation auxiliary circuit; the source of the third auxiliary switch (S _a3 ) and the fourth auxiliary switch ( The drain of S _a4 ) is connected to point R, and the two switches constitute the hysteresis bridge arm (AC-Lead) of the commutation auxiliary circuit; the drain of the first auxiliary switch (S _a1 ) and the third auxiliary switch ( The drain of S _a3 ) is connected to the positive pole of the auxiliary power supply (V _AUX ), the negative pole of the auxiliary power supply (V _AUX ) is connected to the source of the second auxiliary switch tube (S _a2 ), and the source of the fourth auxiliary switch tube (S _a4 ) poles are connected; the same-named end of the primary winding (T1) of the auxiliary converter transformer is connected to the midpoint Q of the leading auxiliary switch arm, and the synonymous end is connected to the midpoint R of the lagging auxiliary switch arm; the excitation inductance (L _m ) in parallel at both ends of the primary winding (T1) of the auxiliary converter transformer; the number of turns of the first winding (T ₂ ) and the second winding (T ₃ ) on the secondary side of the auxiliary converter transformer are the same, and the primary winding (T 3 ) of the auxiliary converter transformer has the same number of turns. The ratio of the number of turns of T1) to the number _of turns of T2 (or T3) is ₁ /n.

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

The circuit is in a stable state, S ₂ , S _a1 , and S _a3 are in a conducting state, and S ₁ , S _a2 , and S _a4 are in an off state; the commutation diodes DN1 , DN2 and the anti-parallel diodes of the switch tubes are in an off state;

At time t0, turn off _Sa3 ;

After S _a3 is turned off, delay DP1 and turn on S _a4 ;

After S _a4 is turned on, DP2 is delayed, and S ₂ is turned off;

After S2 is turned off, delay DP3 and turn _on S1 _;

After S1 is turned _on , delay DP4, and turn off S _a1 ;

After S _a1 is turned off, delay DP5 and turn on S _a2 ;

After S ₁ is turned on, delay T _on , and turn off S ₁ ;

After S1 is turned off, delay DP6 and turn _on S2 _;

At time t0, that is, after S _a3 is turned off, delay T _SW /2, and turn off S _a4 ;

After S _a4 is turned off, DP7 is delayed, and S _a3 is turned on;

After S _a3 is turned on, delay DP8, and turn off S _a2 ;

Turn off S _a2 , delay DP9, and turn on S _a1 ;

When the load current is negative, the working mode and switching time interval are:

The circuit is in a stable state, S ₁ , S _a1 , and S _a3 are in an on state, and S ₂ , S _a2 , and S _a4 are in an off state; the commutation diodes DN1, DN2 and the anti-parallel diodes of the switch tubes are in an off state;

At time t0, turn off _Sa3 ;

After S _a3 is turned off, DN1 is delayed, and S _a4 is turned on;

After S _a4 is turned on, DN2 is delayed, and S ₁ is turned off;

After S2 is turned off, delay DN3 and turn _on S2 _;

After S1 is turned _on , DN4 is delayed, and S _a1 is turned off;

After S _a1 is turned off, DN5 is delayed, and S _a2 is turned on;

Delay T _on after S ₂ is turned on, and turn off S ₂ ;

After S2 is turned off, delay DP6 and turn _on S1 _;

At time t0, that is, after S _a3 is turned off, delay T _SW /2, and turn off S _a4 ;

After S _a4 is turned off, DN7 is delayed, and S _a3 is turned on;

After S _a3 is turned on, DN8 is delayed, and S _a2 is turned off;

Turn off S _a2 , delay DN9, and turn on S _a1 ;

In the above formulas, the relevant parameters of the input quantities are as follows: V _DC is the DC bus voltage; V _AUX is the auxiliary power supply voltage; T _{1A_min} is the shortest ZVS turn-on time of S _a4 ; T _3B is the shortest turn-on time of S ₁ (S ₂ ); I _r is the part of the peak value of commutation current that exceeds the load current; C _{m_oss} is the parallel absorption capacitor of the main switch tubes S ₁ -S ₂ : C _{m_oss} =C ₁ =C ₂ ; C _{a_oss} is the parallel absorption of the auxiliary switch tubes S _a1 -S _a4 Capacitance: C _{a_oss} =C _a1 =C _a2 =C _a3 =C _a4 ;

为辅助开关换流前的激磁电流值，与每个开关周期中的负载电流值成正相关；The following parameters can be expressed according to the input constraints; V' _AUX is the secondary voltage of the transformer; L _r is the commutation inductance; L _m is the magnetizing inductance;

is the excitation current value of the auxiliary switch before commutation, which is positively related to the load current value in each switching cycle;

Wherein T _{14_min} is the time interval between t ₁ and t ₄ obtained by substituting i _Load = 0 after ignoring the current change before charging by the commutating current; T _{1A_min} is the on-time T of S _a4 ZVS when the load current is zero _1A value.

As a further improvement of the above scheme, the bulk parasitic capacitances of the auxiliary switch transistors S _a1 -S _a4 are the same as the external parallel absorption capacitors C _a1 -C _a4 , and are represented by Ca_oss in the following formula; the main switch transistors S ₁ -S ₂ The parasitic capacitance of the body is the same as the external parallel absorption capacitor C1-C2, which is then expressed by Cm_oss in the formula; the following two cases are analyzed for the output current is positive and negative; because the load inductance is large enough, it is considered that in a PWM switch The load current is constant during the cycle; when the output current is positive, the specific description of each mode and the calculation process of the interval time are as follows:

Mode 1 (t<t0): The circuit is in a stable state, and S ₂ is in a conducting state; the load current I _Load is freewheeling through S ₂ , S _a1 and S _a3 are turned on, and the excitation current iL _m is freewheeling through S _a1 and S _a3 , whose value is

从零开始增加；激磁电流

向正方向变化；Mode 2 (t0-t1): at time t0, S _a3 is turned off; the commutation inductance L _r resonates with the auxiliary capacitors C _a3 and C _a4 through the transformer and the magnetizing inductance L _m in parallel, and the potential at point R drops; the commutation inductance current

Increase from zero; magnetizing current

change in the positive direction;

表达式为：In this mode, the voltage at both ends of _{Sa3 v Sa3 and} the primary winding current

The expression is:

和换流电流

According to the relationship between the instantaneous value of the inductor current, the terminal voltage integral and the initial value of the current, the magnetizing inductor current

and commutation current

where ω _a is the resonant angular frequency:

At time t1, the voltage across _Sa3 resonates to V _AUX , and the time according to this resonance mode is:

Mode 3 (t1-T ₂ ): At t1, the potential of point R drops to 0, _Da4 is naturally turned on, Sa4 reaches the ZVS commutation condition, the voltage and current directions at both ends of the magnetizing inductor are reversed, and the magnitude of the magnetizing current decreases linearly; The inductance current increases linearly; at t _A , the primary winding current decreases to zero, and _Sa4 can be controlled to conduct ZVS during the time period t1-tA;

The primary winding current in this mode is:

The soft turn-on time of the auxiliary tube S _a4 is:

The time interval DP1 from when S _a3 is turned off to when S _a4 is turned on is:

The charging mode (t ₁ -t ₂ ) commutation inductor current is:

Among them: V' _AUX is the secondary voltage of the transformer;

的值增至最大值：At time _t2 , the commutation current

to the maximum value:

i _Lr (t ₂ )=I _r +i _Load \*MERGEFORMAT(33)

中超过负载电流的部分Where: I _r is the commutation current

the part that exceeds the load current

Simultaneously, the duration of the charging mode (T _1-2 ) is:

The time interval DP2 from the turn-on of S _a4 to the turn-off of S ₂ is:

Mode 4 (T ₂ -T ₃ ): At time T ₂ , the main switch S ₂ is turned off, and the part I _r of the commutation inductor current i _Lr that exceeds the load current discharges the capacitor C1 and charges the capacitor C2, and the potential at point O begins to resonate and rise;

O point potential v _O and commutation current i _Lr are expressed as:

in:

At time _t3 , the potential of point O rises to V _DC ; the duration of this mode is:

in:

Mode 5 (T3 _- t4): _At time T3, the potential at point O rises to V _DC , D1 is naturally turned _on , and S1 meets the ZVS commutation conditions; the commutation inductor current iL _r decreases linearly, and at tB, the commutation inductor current iL _r is reduced to the load current iLoad; the main switch tube S ₁ can be controlled to conduct between the time period T ₃ -tB to realize ZVS conduction;

By, get: the main switch ZVS open mode duration is:

_The time interval DP3 from when S2 is turned off to when S1 is turned _on is:

The duration of this mode is:

The time interval DP4 from when S ₁ is turned on to when S _a1 is turned off is:

激磁电流

对C_a1充电C_a2放电，Q点电位开始近似线性下降；t5时刻，Q点电位降到0，Da2自然导通；Mode 6 (t4-t6): At time t4, the commutation inductor current iL _r drops to 0A, S _a1 is turned off, and the excitation current iL _m increases to

Exciting current

When C _a1 is charged and C _a2 is discharged, the potential of Q point begins to decrease approximately linearly; at t5 time, the potential of Q point drops to 0, and Da2 is naturally turned on;

t5-t6 is determined by PWM control needs, and S _a2 can be controlled to conduct between t5-t6;

The t ₄ -t ₅ durations are:

The time interval DP5 from when S _a1 is turned off to when S _a2 is turned on is:

DP5=T _4-5 \*MERGEFORMAT(46)

Mode 7 (t6-t8): At time t6, S ₁ is turned off, the load current i _Load charges C1, discharges C2, and the potential of point O decreases linearly; at time t7, the potential of point O drops to 0, and the diode D2 is naturally turned on; S ₂ can be turned on after t7;

The t ₆ -t ₇ durations are:

_The time interval DP6 from when S1 is turned off to when S2 is turned _on is:

DP6=T _6-7 \*MERGEFORMAT(48)

对C_a4充电C_a3放电，R点电位开始上升；Mode 8 (t8-t9): At time t8, turn off _Sa4 , the excitation current

Charge C _a4 and discharge C _a3 , the potential of R point begins to rise;

表达式为：R point potential v _R and current

The expression is:

in:

At time t ₉ , the potential at point R resonates to V _AUX , and the duration of this mode is:

Mode 9 (t9-t10): At t9, the potential at point R rises to V _AUX Da3 turns on naturally, S _a3 reaches the ZVS commutation condition, and at tC, the excitation current decreases to zero; S _a3 can be controlled between time periods T9C turn on;

The excitation current in this mode is:

The soft turn-on time of S _a3 is:

The time interval DP7 from when S _a4 is turned off to when S _a3 is turned on is:

增至

本模式持续时间为：At time t ₁₀ , the excitation current

increase to

The duration of this mode is:

The time interval DP8 from when S _a3 is turned on to when S _a2 is turned off is:

对C_a2充电C_a1放电，Q点电位近似线性上升；t11时刻，P点电位升至V_AUX，Da1自然导通；在下一个开关周期之前控制导通S_a1；Mode 10 (t10-t11): at time t10, turn off _Sa2 ; auxiliary converter transformer excitation current

When C _a2 is charged and C _a1 is discharged, the potential of point Q rises approximately linearly; at time t11, the potential of point P rises to V _AUX , and Da1 is naturally turned on; before the next switching cycle, S _a1 is controlled to be turned on;

The duration of this mode is:

The time interval DP9 from when S _a2 is turned off to when S _a1 is turned on is:

DP9=T _10-11 \*MERGEFORMAT(59)

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

Mode 1 (t<t0): The circuit is in a stable state, and S ₁ is in a conducting state; the load current I _Load is freewheeling through S ₁ , S _a1 and S _a3 are turned on, and the excitation current iL _m is freewheeling through S _a1 and S _a3 , whose value is

从零开始增加；激磁电流

向正变化；Mode 2 (t0-t1): At time t0, S _a3 is turned off; the commutating inductance L _r is connected in parallel with the auxiliary capacitors C _a3 and C _a4 through the transformer and the magnetizing inductance L _m , and the potential of the R point drops. The equivalent circuit diagram is as follows Figure 6; commutation inductor current

Increase from zero; magnetizing current

positive change

In this mode, the voltage v _Sa3 across both ends of _Sa3 and the primary winding current i _N are expressed as:

和换流电流

According to the relationship between the instantaneous value of the inductor current, the terminal voltage integral and the initial value of the current, the magnetizing inductor current

and commutation current

where ω _a is the resonant angular frequency:

At time t1, the voltage across _Sa3 resonates to V _AUX , and the time according to this resonance mode is:

Mode 3 (t1-T ₂ ): At t1, the potential at point R drops to 0, _Da4 is naturally turned on, and Sa4 reaches the ZVS commutation condition. Figure 7 is the equivalent circuit diagram of this mode; the voltage and current directions at both ends of the magnetizing inductor In the reverse direction, the magnitude of the excitation current decreases linearly; the current of the commutation inductor increases linearly; at t _A , the primary winding current decreases to zero, and _Sa4 can be controlled to conduct ZVS during the time period t1-tA;

The primary winding current in this mode is:

The soft turn-on time of the auxiliary tube S _a4 is:

The time interval DN1 from when S _a3 is turned off to when S _a4 is turned on is:

The charging mode (t ₁ -t ₂ ) commutation inductor current is:

Among them: V' _AUX is the secondary voltage of the transformer;

的值增至最大值：At time _t2 , the commutation current

to the maximum value:

i _Lr (t ₂ )=I _r +i _Load \*MERGEFORMAT(70)

中超过负载电流的部分Where: I _r is the commutation current

the part that exceeds the load current

Simultaneously, the duration of the charging mode (T _1-2 ) is:

The time interval DN2 from the turn-on of S _a4 to the turn-off of S ₁ is:

Mode 4 (T ₂ -T ₃ ) _: At time T2, the main switch S ₁ is turned off, and Figure 8 is the equivalent circuit diagram of this mode; the part I _r of the commutation inductor current i _Lr that exceeds the load current discharges the capacitor C2 C1 After charging, the potential at point O begins to resonate and drop;

O point potential v _O and commutation current i _Lr are expressed as:

in:

At time t ₃ , the potential of point O drops to 0; the duration of this mode is:

in:

Mode 5 (T ₃ -t4): At the time of T ₃ , D2 is naturally turned on, and S ₂ meets the ZVS commutation conditions; the commutation inductor current iL _r decreases linearly, and at tB, the commutation inductor current iL _r decreases to the load current iLoad ; The main switch tube S ₂ can be controlled to conduct during the time period T ₃ -tB;

From, get: the main switch ZVS on duration is:

_The time interval DN3 from when S1 is turned off to when S2 is turned _on is:

The duration of this mode is:

The time interval DN4 from the turn-on of S ₂ to the turn-off of S _a1 is:

激磁电流

对C_a1充电C_a2放电，Q点电位开始近似线性下降；t5时刻，Q点电位降到0，Da2自然导通；t5-t6由PWM控制需要确定,S_a2可在t5-t6之间控制导通；Mode 6 (t4-t6): At time t4, S _a1 is turned off, the commutation inductor current iL _r drops to 0A, and the excitation current iL _m reversely increases to

Exciting current

When C _a1 is charged and C _a2 is discharged, the potential of Q point begins to decrease approximately linearly; at t5 time, the potential of Q point drops to 0, and Da2 is naturally turned on; t5-t6 is determined by PWM control, and S _a2 can be controlled between t5-t6 turn on;

The t ₄ -t ₅ durations are:

The time interval DN5 from when S _a1 is turned off to when S _a2 is turned on is:

DN5＝T _4-5 \*MERGEFORMAT(83)

Mode 7 (t6-t8): At time t6, S ₂ is turned off, the load current i _Load charges C2, C1 discharges, and the line at point O decreases; at time t7, the potential at point O rises to V _DC , and diode D1 is naturally turned on; t7-t8 is determined by PWM control needs, and S1 can be controlled to be turned _on after t7;

The t ₆ -t ₇ durations are:

_The time interval _DN6 from when S2 is turned off to when S1 is turned on is:

DN6＝T _6-7 \*MERGEFORMAT(85)

对C_a4充电C_a3放电，R点电位开始上升；Mode 8 (t8-t9): At time t8, S _a4 is turned off. The equivalent circuit diagram of this mode is shown in Figure 9. The excitation current

Charge C _a4 and discharge C _a3 , the potential of R point begins to rise;

表达式为：R point potential v _R and current

The expression is:

in:

At time t ₉ , the potential at point R resonates to V _AUX , and the duration of this mode is:

Mode 9 (t9-t10): At time t9, the potential at point R rises to V _AUX , Da3 turns on naturally, Sa3 reaches the ZVS commutation condition, and at time tC, the excitation current decreases to zero; _Sa3 can be between time periods _T9C control conduction;

The excitation current in this mode is:

The soft turn-on time of S _a3 is:

The time interval DN7 from when S _a4 is turned off to when S _a3 is turned on is:

增至

本模式持续时间为：At time t ₁₀ , the excitation current

increase to

The duration of this mode is:

The time interval DN8 from when S _a3 is turned on to when S _a2 is turned off is:

对C_a2充电C_a1放电，Q点电位近似线性上升；t11时刻，P点电位升至V_AUX，Da1自然导通；在下一个开关周期之前控制导通S_a1；Mode 10 (t10-t11): at time t10, turn off _Sa2 ; auxiliary converter transformer excitation current

When C _a2 is charged and C _a1 is discharged, the potential of point Q rises approximately linearly; at time t11, the potential of point P rises to V _AUX , and Da1 is naturally turned on; before the next switching cycle, S _a1 is controlled to be turned on;

The duration of this mode is:

The time interval DN9 from when S _a2 is turned off to when S _a1 is turned on is:

DN9=T _10-11 \*MERGEFORMAT(96)

From the analysis of the above circuit structure and working principle, it can be seen that the main switch needs to design the commutation inductance, transformer turns ratio, and switch parallel absorption capacitor to complete the zero-voltage commutation; the auxiliary switch needs to design the magnetizing inductance to complete the zero-voltage commutation; The design will be done as follows (analyzed with the output current as the timing);

When V' _AUX is less than V _DC / ₂ , turn off S2 under the condition that the commutation current is greater than a certain value of the load current to ensure that the switch tube can reliably complete the commutation; and the turn-off loss of the main switch is related to the channel current at the time of turn-off. is proportional to the square of [8, 13], so when the turn-off current of S ₂ satisfies the formula, the turn-off loss of the main switch can be approximately ignored (the turn-off loss is less than 1/10):

Among them, I _{Load_rms} is the effective value of the load current;

In the actual circuit operation process, there is an error in the detection of the load current, which leads to the error of I _r , which affects the commutation time T _2-3 and the S ₁ ZVT turn-on time _{T 3B} . When _r satisfies the formula, the dead time of the main switch can be a fixed value;

Simultaneous,,:

From, get:

The range of values for β that can be obtained from the sum solution is:

In order to ensure that the lag arm can be commutated reliably and that S _a4 has enough ZVS turn-on time, simultaneously, we get:

In order to ensure that the magnetizing current is equal in magnitude and opposite in direction after the linear discharge stage of the commutation inductor L _r (t=t ₄ ) and before the linear charging stage of the resonant inductor L _r (t=t ₁ ) (ignoring the primary lag arm resonance commutation stage) change in magnetizing current):

不同；由和可看出当负载电流为0时，根据S_a4最短ZVS时间T_{1A_min}计算出的L_m符合任何负载电流大于0时S_a4有足够得ZVS开通时间的要求；where T ₁₄ is the time interval of t ₁ -t ₄ obtained from the sum of the different loads, , so that the

It can be seen from the sum that when the load current is 0, the _Lm calculated according to the shortest ZVS time T _{1A_min} of _Sa4 meets the requirement that _Sa4 has sufficient ZVS turn-on time when the load current is greater than 0;

Substitute i _Load = 0 into the formula , , and the time interval of t ₁ -t ₄ obtained by the sum:

T ₁₄ =T _{14_min} \*MERGEFORMAT(104)

Simultaneous:

Among them, T _{1A_min} is the value of the on-time T _1A of the _Sa4 ZVS when the load current is 0.

The beneficial effects of the present invention are:

Compared with the prior art, the circuit of the present invention maintains the prior art by using the phase correlation method, realizes the advantage of zero-voltage turn-on of the main switch tube, and reduces the switching loss of the main switch. The energy storage in the magnetizing inductance realizes zero-voltage turn-on and its withstand voltage value is much smaller than that of the main switch; and the magnetizing current reset is reliably realized in each switching cycle, which effectively reduces the volume of the transformer; the transformer secondary winding is coupled The overvoltage problem of the auxiliary commutating diodes D _c1 and D _c2 is solved.

Description of drawings

The specific embodiments of the present invention will be described in further detail below in conjunction with the accompanying drawings, wherein:

1 is a soft-switching inverter circuit using two transformers in an auxiliary circuit of the prior art;

Fig. 2 is a soft-switching inverter circuit using two transformers in the auxiliary circuit of the prior art;

Fig. 3 is the auxiliary resonant commutated pole inverter circuit of the present invention with bidirectional reset of phase-related magnetizing current;

Fig. 4 is the circuit state diagram of each mode in a PWM switching cycle when the output current of the circuit of the present invention is positive;

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

6 is an equivalent circuit diagram of Mode 2 in one PWM switching cycle in the present invention;

7 is an equivalent circuit diagram of Mode 3 in one PWM switching cycle in the present invention;

8 is an equivalent circuit diagram of mode 4 in one PWM switching cycle in the present invention;

9 is an equivalent circuit diagram of mode 8 in one PWM switching cycle in the present invention;

Fig. 10 is the waveform diagram of the driving pulse signal of each switch tube and the main node voltage and branch current in one PWM switching cycle when the output current of the circuit of the present invention is positive;

11 is a waveform diagram of the driving pulse signal of each switch tube and the voltage and current of the main node in one PWM switching cycle when the output current of the circuit of the present invention is negative.

Detailed ways

As shown in FIG. 1-FIG. 11 , an auxiliary resonant commutated pole inverter with bidirectional reset of phase-related magnetizing current provided by the present invention includes a first main switch tube S ₁ , a second main switch tube S ₂ , a second main switch tube S 2 , and a second main switch tube S 2 . A commutating diode D _c1 , the second commutating diode D _c2 , the DC power supply V _DC , the auxiliary power supply V _AUX , the load Load, the magnetizing inductance L _m , the first voltage dividing capacitor C _d1 and the second voltage dividing capacitor C _d2 , resonance Inductance L _r , the first winding T ₂ on the secondary side of the auxiliary converter transformer, the second winding T ₃ on the secondary side of the auxiliary converter transformer, the first auxiliary switch tube S _a1 , the second auxiliary switch tube S _a2 , and the third auxiliary switch tube S _a3 , the fourth auxiliary switch S _a4 , the leading bridge arm AC-Lag, and the lagging bridge arm AC-Lead; the source of the _first main switch S1 and the drain of the _second main switch S2 are connected to O The two switch tubes constitute the main switch bridge arm; the drain of the first main switch tube S ₁ and the negative pole of the first commutation diode D _c1 are connected to the positive pole of the DC power supply V _DC ; the negative pole of the DC power supply V _DC is connected to the The source of the two main switch tubes S ₂ is connected to the positive pole of the second commutation diode D _c2 ; one end of the load Load is connected to the midpoint O of the bridge arm of the main switch, and the other end is connected to the first voltage dividing capacitor C _d1 and the second dividing capacitor C d1. The midpoint of the piezoelectric capacitor C _d2 is connected; one end of the resonant inductance L _r is connected to the midpoint O of the main switch bridge arm, and the other end is connected to the other end of the first winding T ₂ on the secondary side of the auxiliary converter transformer, and the auxiliary converter transformer The same-named end of the second winding T3 on the secondary side is connected to point P; the same _- named end of the first winding T2 _on the secondary side of the auxiliary converter transformer is connected with the positive electrode of the first converter diode _Dc1 ; the second winding on the secondary side of the auxiliary converter transformer is connected _The synonym terminal of T3 is connected to the negative electrode of the second commutation diode D _c2 ; the source of the first auxiliary switch S _a1 and the drain of the second auxiliary switch S _a2 are connected to the Q point, and these two switches constitute The leading bridge arm AC-Lag of the commutation auxiliary circuit; the source of the third auxiliary switch S _a3 and the drain of the fourth auxiliary switch S _a4 are connected to point R, and these two switches constitute the lag of the commutation auxiliary circuit Bridge arm AC-Lead; the drain of the first auxiliary switch tube S _a1 and the drain of the third auxiliary switch tube S _a3 are connected to the positive pole of the auxiliary power supply V _AUX , and the negative pole of the auxiliary power supply V _AUX is connected to the second auxiliary switch tube S _a2 The source of the fourth auxiliary switch tube S _a4 is connected to the source of the fourth auxiliary switch; the same name terminal of the primary winding T1 of the auxiliary converter transformer is connected to the midpoint Q point of the leading auxiliary switch bridge arm, and the synonym terminal is connected to the lagging auxiliary switch bridge arm. The midpoint R point is connected; the exciting inductance _Lm is connected in parallel with both ends of the 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 are the same, and the original winding of the auxiliary converter transformer has the same number of turns. The ratio of the number of turns of the side winding T1 to the number _of turns of T2 or T3 is ₁ /n.

Further improvement, when the load current is positive, the working mode and the switching time interval are:

The circuit is in a stable state, S ₂ , S _a1 , and S _a3 are in a conducting state, and S ₁ , S _a2 , and S _a4 are in an off state; the commutation diodes DN1 , DN2 and the anti-parallel diodes of the switch tubes are in an off state;

At time t0, turn off _Sa3 ;

After S _a3 is turned off, delay DP1 and turn on S _a4 ;

After S _a4 is turned on, DP2 is delayed, and S ₂ is turned off;

After S2 is turned off, delay DP3 and turn _on S1 _;

After S1 is turned _on , delay DP4, and turn off S _a1 ;

After S _a1 is turned off, delay DP5 and turn on S _a2 ;

After S ₁ is turned on, delay T _on , and turn off S ₁ ;

After S1 is turned off, delay DP6 and turn _on S2 _;

At time t0, that is, after S _a3 is turned off, delay T _SW /2, and turn off S _a4 ;

After S _a4 is turned off, DP7 is delayed, and S _a3 is turned on;

After S _a3 is turned on, delay DP8, and turn off S _a2 ;

Turn off S _a2 , delay DP9, and turn on S _a1 ;

When the load current is negative, the working mode and switching time interval are:

The circuit is in a stable state, S ₁ , S _a1 , and S _a3 are in an on state, and S ₂ , S _a2 , and S _a4 are in an off state; the commutation diodes DN1, DN2 and the anti-parallel diodes of the switch tubes are in an off state;

At time t0, turn off _Sa3 ;

After S _a3 is turned off, DN1 is delayed, and S _a4 is turned on;

After S _a4 is turned on, DN2 is delayed, and S ₁ is turned off;

After S2 is turned off, delay DN3 and turn _on S2 _;

After S1 is turned _on , DN4 is delayed, and S _a1 is turned off;

After S _a1 is turned off, DN5 is delayed, and S _a2 is turned on;

Delay T _on after S ₂ is turned on, and turn off S ₂ ;

After S2 is turned off, delay DP6 and turn _on S1 _;

At time t0, that is, after S _a3 is turned off, delay T _SW /2, and turn off S _a4 ;

After S _a4 is turned off, DN7 is delayed, and S _a3 is turned on;

After S _a3 is turned on, DN8 is delayed, and S _a2 is turned off;

Turn off S _a2 , delay DN9, and turn on S _a1 ;

In the above formulas, the relevant parameters of the input quantities are as follows: V _DC is the DC bus voltage; V _AUX is the auxiliary power supply voltage; T _{1A_min} is the shortest ZVS turn-on time of S _a4 ; T _3B is the shortest turn-on time of S ₁ (S ₂ ); I _r is the part of the peak value of commutation current that exceeds the load current; C _{m_oss} is the parallel absorption capacitor of the main switch tubes S ₁ -S ₂ : C _{m_oss} =C ₁ =C ₂ ; C _{a_oss} is the parallel absorption of the auxiliary switch tubes S _a1 -S _a4 Capacitance: C _{a_oss} =C _a1 =C _a2 =C _a3 =C _a4 ;

为辅助开关换流前的激磁电流值，与每个开关周期中的负载电流值成正相关；The following parameters can be expressed according to the input constraints; V' _AUX is the secondary voltage of the transformer; L _r is the commutation inductance; L _m is the magnetizing inductance;

is the excitation current value of the auxiliary switch before commutation, which is positively related to the load current value in each switching cycle;

Wherein T _{14_min} is the time interval between t ₁ and t ₄ obtained by substituting i _Load = 0 after ignoring the current change before charging by the commutating current; T _{1A_min} is the on-time T of S _a4 ZVS when the load current is zero _1A value.

The body parasitic capacitances of the auxiliary switches S _a1 -S _a4 are the same as the external parallel absorption capacitors C _a1 -C _a4 , and are represented by C _{a_oss} in the following formula; the body parasitic capacitances of the main switch tubes S ₁ -S ₂ are absorbed in parallel with the external Capacitors C ₁ -C ₂ have the same value, and are represented by C _{m_oss} in the following formula.

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

In the following, the two cases of positive and negative output current are analyzed respectively. Since the load inductance is large enough, the load current is considered to be constant during one PWM switching cycle.

The reference positive direction of each electrical variable in the loop is consistent with the direction of the arrow in Figure 3.

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

Mode 1 (t<t0): The circuit is in a stable state, and S ₁ is in a conducting state; the load current I _Load is freewheeling through S ₁ , S _a1 and S _a3 are turned on, and the excitation current iL _m is freewheeling through S _a1 and S _a3 , whose value is

从零开始增加；激磁电流

向正变化；Mode 2 (t0-t1): At time t0, S _a3 is turned off; the commutating inductance L _r is connected in parallel with the auxiliary capacitors C _a3 and C _a4 through the transformer and the magnetizing inductance L _m , and the potential of the R point drops. The equivalent circuit diagram is as follows Figure 6; commutation inductor current

Increase from zero; magnetizing current

positive change

In this mode, the voltage v _Sa3 across both ends of _Sa3 and the primary winding current i _N are expressed as:

和换流电流

According to the relationship between the instantaneous value of the inductor current, the terminal voltage integral and the initial value of the current, the magnetizing inductor current

and commutation current

where ω _a is the resonant angular frequency:

At time t1, the voltage across _Sa3 resonates to V _AUX , and the time according to this resonance mode is:

Mode 3 (t1-T ₂ ): At t1, the potential at point R drops to 0, _Da4 is naturally turned on, and Sa4 reaches the ZVS commutation condition. Figure 7 is the equivalent circuit diagram of this mode; the voltage and current directions at both ends of the magnetizing inductor In the reverse direction, the magnitude of the excitation current decreases linearly; the current of the commutation inductor increases linearly; at t _A , the primary winding current decreases to zero, and _Sa4 can be controlled to conduct ZVS during the time period t1-tA;

The primary winding current in this mode is:

The soft turn-on time of the auxiliary tube S _a4 is:

The time interval DN1 from when S _a3 is turned off to when S _a4 is turned on is:

The charging mode (t ₁ -t ₂ ) commutation inductor current is:

Among them: V' _AUX is the secondary voltage of the transformer;

的值增至最大值：At time _t2 , the commutation current

to the maximum value:

i _Lr (t ₂ )=I _r +i _Load \*MERGEFORMAT(70)

中超过负载电流的部分Where: I _r is the commutation current

the part that exceeds the load current

Simultaneously, the duration of the charging mode (T _1-2 ) is:

The time interval DN2 from the turn-on of S _a4 to the turn-off of S ₁ is:

Mode 4 (T ₂ -T ₃ ) _: At time T2, the main switch S ₁ is turned off, and Figure 8 is the equivalent circuit diagram of this mode; the part I _r of the commutation inductor current i _Lr that exceeds the load current discharges the capacitor C2 C1 After charging, the potential at point O begins to resonate and drop;

O point potential v _O and commutation current i _Lr are expressed as:

in:

At time t ₃ , the potential of point O drops to 0; the duration of this mode is:

in:

Mode 5 (T ₃ -t4): At the time of T ₃ , D2 is naturally turned on, and S ₂ meets the ZVS commutation conditions; the commutation inductor current iL _r decreases linearly, and at tB, the commutation inductor current iL _r decreases to the load current iLoad ; The main switch tube S ₂ can be controlled to conduct during the time period T ₃ -tB;

From, get: the main switch ZVS on duration is:

_The time interval DN3 from when S1 is turned off to when S2 is turned _on is:

The duration of this mode is:

The time interval DN4 from the turn-on of S ₂ to the turn-off of S _a1 is:

激磁电流

对C_a1充电C_a2放电，Q点电位开始近似线性下降；t5时刻，Q点电位降到0，Da2自然导通；t5-t6由PWM控制需要确定,S_a2可在t5-t6之间控制导通；Mode 6 (t4-t6): At time t4, S _a1 is turned off, the commutation inductor current iL _r drops to 0A, and the excitation current iL _m reversely increases to

Exciting current

When C _a1 is charged and C _a2 is discharged, the potential of Q point begins to decrease approximately linearly; at t5 time, the potential of Q point drops to 0, and Da2 is naturally turned on; t5-t6 is determined by PWM control, and S _a2 can be controlled between t5-t6 turn on;

The t ₄ -t ₅ durations are:

The time interval DN5 from when S _a1 is turned off to when S _a2 is turned on is:

DN5＝T _4-5 \*MERGEFORMAT(83)

Mode 7 (t6-t8): At time t6, S ₂ is turned off, the load current i _Load charges C2, C1 discharges, and the line at point O decreases; at time t7, the potential at point O rises to V _DC , and diode D1 is naturally turned on; t7-t8 is determined by PWM control needs, and S1 can be controlled to be turned _on after t7;

The t ₆ -t ₇ durations are:

_The time interval _DN6 from when S2 is turned off to when S1 is turned on is:

DN6＝T _6-7 \*MERGEFORMAT(85)

对C_a4充电C_a3放电，R点电位开始上升；Mode 8 (t8-t9): At time t8, S _a4 is turned off. The equivalent circuit diagram of this mode is shown in Figure 9. The excitation current

Charge C _a4 and discharge C _a3 , the potential of R point begins to rise;

表达式为：R point potential v _R and current

The expression is:

in:

At time t ₉ , the potential at point R resonates to V _AUX , and the duration of this mode is:

Mode 9 (t9-t10): At time t9, the potential at point R rises to V _AUX , Da3 turns on naturally, Sa3 reaches the ZVS commutation condition, and at time tC, the excitation current decreases to zero; _Sa3 can be between time periods _T9C control conduction;

The excitation current in this mode is:

The soft turn-on time of S _a3 is:

The time interval DN7 from when S _a4 is turned off to when S _a3 is turned on is:

增至

本模式持续时间为：At time t ₁₀ , the excitation current

increase to

The duration of this mode is:

The time interval DN8 from when S _a3 is turned on to when S _a2 is turned off is:

对C_a2充电C_a1放电，Q点电位近似线性上升；t11时刻，P点电位升至V_AUX，Da1自然导通；在下一个开关周期之前控制导通S_a1；Mode 10 (t10-t11): at time t10, turn off _Sa2 ; auxiliary converter transformer excitation current

When C _a2 is charged and C _a1 is discharged, the potential of point Q rises approximately linearly; at time t11, the potential of point P rises to V _AUX , and Da1 is naturally turned on; before the next switching cycle, S _a1 is controlled to be turned on;

The duration of this mode is:

The time interval DN9 from when S _a2 is turned off to when S _a1 is turned on is:

DN9=T _10-11 \*MERGEFORMAT(96)

From the analysis of the above circuit structure and working principle, it can be seen that the main switch needs to design the commutation inductance, transformer turns ratio, and switch parallel absorption capacitor to complete the zero-voltage commutation; the auxiliary switch needs to design the magnetizing inductance to complete the zero-voltage commutation; The design will be done as follows (analyzed with the output current as the timing);

When V' _AUX is less than V _DC / ₂ , turn off S2 under the condition that the commutation current is greater than a certain value of the load current to ensure that the switch tube can reliably complete the commutation; and the turn-off loss of the main switch is related to the channel current at the time of turn-off. is proportional to the square of [8, 13], so when the turn-off current of S ₂ satisfies the formula, the turn-off loss of the main switch can be approximately ignored (the turn-off loss is less than 1/10):

Among them, I _{Load_rms} is the effective value of the load current;

In the actual circuit operation process, there is an error in the detection of the load current, which leads to the error of I _r , which affects the commutation time T _2-3 and the S ₁ ZVT turn-on time _{T 3B} . When _r satisfies the formula, the dead time of the main switch can be a fixed value;

Simultaneous,,:

From, get:

The range of values for β that can be obtained from the sum solution is:

In order to ensure that the lag arm can be commutated reliably and that S _a4 has enough ZVS turn-on time, simultaneously, we get:

In order to ensure that the magnetizing current is equal in magnitude and opposite in direction after the linear discharge stage of the commutation inductor L _r (t=t ₄ ) and before the linear charging stage of the resonant inductor L _r (t=t ₁ ) (ignoring the primary lag arm resonance commutation stage) change in magnetizing current):

不同；由和可看出当负载电流为0时，根据S_a4最短ZVS时间T_{1A_min}计算出的L_m符合任何负载电流大于0时S_a4有足够得ZVS开通时间的要求；where T ₁₄ is the time interval of t ₁ -t ₄ obtained from the sum of the different loads, , , so the time interval of each switching cycle is

It can be seen from the sum that when the load current is 0, the _Lm calculated according to the shortest ZVS time T _{1A_min} of _Sa4 meets the requirement that _Sa4 has sufficient ZVS turn-on time when the load current is greater than 0;

Substitute i _Load = 0 into the formula , , and the time interval of t ₁ -t ₄ obtained by the sum:

T ₁₄ =T _{14_min} \*MERGEFORMAT(104)

Simultaneous:

Among them, T _{1A_min} is the value of the on-time T _1A of the _Sa4 ZVS when the load current is 0.

The input parameters are shown in Table 1:

Input DC voltage (V_DC) 400V Auxiliary voltage (V_AUX) 20V Switching frequency (f_sw) 20KHz _{m_oss} 100pF _{a_oss} 1000pF I_r 2A T_{1A_min} 10ns T_3B 10ns

Table 1 Input parameters The specific values of the inductance and transformer calculated according to the constraints of the input parameters are shown in Table 2

Commutation Inductance (L_r) 4.21uH Magnetizing Inductance (L_m) 1.06uH Transformer secondary voltage (V′_AUX) 60V

Table 2

和各持续时间与负载电流的关系如下：

The relationship between each duration and load current is as follows:

The above embodiments are not limited to the technical solutions of the embodiments themselves, and the embodiments can be combined with each other to form new embodiments. The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention should be included within the scope of the technical solutions of the present invention.

Claims (3)

1. An auxiliary resonance converter pole inverter with phase-correlated magnetizing current bidirectional reset is characterized in that: comprises a first main switch tube (S)₁) A second main switch tube (S)₂) A first commutation diode (D)_c1) A second commutation diode (D)_c2) DC power supply (V)_DC) Auxiliary power supply (V)_AUX) A load (L oad) and an excitation inductor (L)_m) A first voltage-dividing capacitor C_d1A second voltage dividing capacitor C_d2Resonant inductor (L)_r) Auxiliary converter transformer secondary side first winding (T)₂) And a secondary side second winding (T) of the auxiliary converter transformer₃) A first auxiliary switch tube (S)_a1) A second auxiliary switch tube (S)_a2) And the third auxiliary switch tube (S)_a3) And the fourth auxiliary switch tube (S)_a4) The first main switch tube (S), a leading bridge arm (AC-L ag) and a lagging bridge arm (AC-L ead)₁) Source electrode, second main switch tube (S)₂) The drain electrode of the switch tube is connected with a point O, and the two switch tubes form a main switch bridge arm; first main switch tube (S)₁) The first commutation diode (D)_c1) And a DC power supply (V)_DC) The positive electrodes are connected; DC power supply (V)_DC) Negative pole of (1) and second main switching tube (S)₂) Source of (D), second commutation diode (D)_c2) One end of a load (L oad) is connected with a point O of the middle point of a bridge arm of the main switch, and the other end of the load is connected with two first voltage-dividing capacitors C_d1A second voltage dividing capacitor C_d2Is connected with the midpoint of the resonant inductor (L)_r) One end of the auxiliary converter transformer is connected with the midpoint O of the main switch bridge arm, and the other end of the auxiliary converter transformer is connected with the auxiliary side first winding (T)₂) End of different name, auxiliary converter transformer secondary side second winding (T)₃) The homonymous end of the point P is connected with the point P; auxiliary converter transformer secondary first winding (T)₂) And the first commutation diode (D)_c1) The positive electrodes of the two electrodes are connected; secondary winding (T) of auxiliary converter transformer₃) And a second commutation diode (D)_c2) The negative electrodes are connected; first auxiliary switch tube (S)_a1) And a second auxiliary switching tube (S)_a2) The two switching tubes form a leading arm (AC-L ag) of the commutation auxiliary circuit, and a third auxiliary switching tube (S)_a3) Source electrode of (1) and fourth auxiliary switching tube (S)_a4) The two switching tubes form a hysteresis bridge arm (AC-L ead) of the commutation auxiliary circuit, and a first auxiliary switching tube (S)_a1) And a third auxiliary switching tube (S)_a3) Drain electrode of (2) and auxiliary power supply (V)_AUX) Is connected with an auxiliary power supply (V)_AUX) And a second auxiliary switch tube (S)_a2) Source electrode of (1), fourth auxiliary switching tube (S)_a4) The same-name end of a primary winding (T1) of the auxiliary converter transformer is connected with a point Q of a midpoint of a leading auxiliary switch bridge arm, a different-name end is connected with a point R of a midpoint of a lagging auxiliary switch bridge arm, and an excitation inductor (L)_m) Is connected in parallel with two ends of a primary winding (T1) of the auxiliary converter transformer; auxiliary converter transformer secondary first winding (T)₂) And a second winding (T)₃) Has the same number of turns, and the number of turns of the primary winding (T1) of the auxiliary converter transformer is equal to the number of turns of the primary winding (T1)₂(or T)₃) The turns ratio of (1/n).

2. An auxiliary resonant commutating pole inverter with bidirectional reset of phase-correlated magnetizing current according to 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; the commutation diodes DN1 and DN2 and the anti-parallel diode of the switch tube are in an off state;

at time t0, 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 turn-off, turn on S₁；

S₁Delay DP4 after switching on, turn off S_a1；

S_a1Delay DP5 after turn-off, turn on S_a2；

S₁Delay after conduction T_onTurn off S₁；

S₁Delay DP6 after turn-off, turn on S₂；

At time t0, i.e. S_a3Delay after shutdown T_SW/2Turn 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 as follows:

the circuit is in a steady state, S₁、S_a1、S_a3In the on state, S₂、S_a2、S_a4In an off state; the commutation diodes DN1 and DN2 and the switch tube antiparallel diode are in an off state;

at time t0, 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；

S₂DN3 is delayed after the switch-off, and S is conducted₂；

S₁DN4 is delayed after conduction and S is turned off_a1；

S_a1DN5 is delayed after the switch-off, and S is conducted_a2；

S₂Delay after conduction T_onTurn off S₂；

S₂Delay DP6 after turn-off, turn on S₁；

At time t0, i.e. S_a3Delay after shutdown T_SW/2Turn 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；

Off S_a2Delay DN9, turn on S_a1；

In the above equations, the input parameters are as follows: v_DCIs a dc bus voltage; v_AUXIs the auxiliary supply voltage; t is_{1A_min}Is S_a4Shortest ZVS on-time; t is_3BIs S₁(S₂) Shortest turn-on time; 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；

The following parameters can be expressed in terms of input quantity constraints; v'_AUXFor secondary side voltage of transformer L_rL for commutation inductance_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_{14_min}To ignore the current change before charging the commutation current, i_LoadT obtained by adding 0₁-t₄The time interval of (c); t is_{1A_min}When the load current is 0, S_a4ZVS on time T_1AThe value of (c).

3. An auxiliary resonant commutating pole inverter with bidirectional reset of phase-correlated magnetizing current according to claim 2, characterized by: the auxiliary switch tube S_a1-S_a4The body parasitic capacitance and the external parallel absorption capacitance C_a1-C_a4Values are the same, and Ca _ oss is used for expression in the formula; main switch tube S₁-S₂The value of the body parasitic capacitance is the same as that of the external parallel absorption capacitance C1-C2, and Cm _ oss is used for expression in the formula; the following two cases of positive and negative output current are analyzed respectively; since the load inductance is large enough, the load current is considered constant within one PWM switching period; 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)<t 0): the circuit is in a steady state, S₂In a conducting state; load current I_LoadBy S₂Follow current, S_a1、S_a3Conducting, exciting current i L_mBy S_a1、S_a3Free flow of value of

Mode 2(t0-t 1): at time t0, turn off S_a3Commutation inductor L_rPassing through a transformer and an excitation inductor L_mAfter being connected in parallel with an auxiliary capacitor C_a3、C_a4Resonance occurs, the potential at the R point drops, and the current of the current conversion inductor is changed

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 time t1, S_a3Voltage resonance at both ends to V_AUXThe time according to the present resonance mode is:

mode 3 (T1-T)₂): at the time of t1, the potential at the point R is reduced to 0, Da4 is naturally conducted, and S_a4The ZVS commutation condition is achieved, the voltage at two ends of the excitation inductor is opposite to the current direction, and the magnitude of the excitation 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_a4The conduction can be controlled to be ZVS conduction between the time period t 1-tA;

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: (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\*MERGEFORMAT(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 S₂Turn-off, commutation of the inductive current i_LrPart I of the medium excess load current_rDischarging the capacitor C1 and charging the capacitor C2, 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(ii) a The mode duration is:

wherein:

mode 5 (T)₃-t4):T₃At that time, the potential at the point O rises to V_DCD1 is naturally on, S₁Meeting ZVS commutation condition, commutating inductance current i L_rLinear droop, at time tB, commutating inductor current i L_rDown to load current i L oad, and main switch tube S₁May be in the time period T₃-control conduction between tB to achieve ZVS conduction;

thus, obtaining: the duration of the ZVS on mode of the main switch is as follows:

S₂turn off to S₁The on-time interval DP3 is:

the mode duration is:

S₁is conducted to S_a1The off-time interval DP4 is:

mode 6(t4-t6) commutation inductor current i L at time t4_rFalls to 0A, turns off S_a1Excitation current i L_mIs increased to

Excitation current

To C_a1Charging C_a2Discharging, and enabling the potential of the point Q to start to approximately linearly decrease; at the time of t5, the potential at the point Q is reduced to 0, and Da2 leads to the natural conductionOpening;

t5-t6 is determined by PWM control requirements, S_a2The conduction can be controlled between t5 and t 6;

t₄-t₅the duration is:

S_a1turn off to S_a2The on-time interval DP5 is:

DP5＝T_4-5\*MERGEFORMAT(46)

mode 7(t6-t8) time t6, turn off S₁Load current i_LoadC1 is charged, C2 is discharged, and the potential at the point O linearly drops; at the time t7, the potential at the point O is reduced to 0, and the diode D2 is naturally conducted; s₂Conduction may be controlled after t 7;

t₆-t₇the duration is:

S₁turn off to S₂The on-time interval DP6 is:

DP6＝T_6-7\*MERGEFORMAT(48)

mode 8(t8-t9) time t8, turn off S_a4Exciting 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(t9-t10) when the potential at the point R rises to V at time t9_AUXDa3 is naturally turned on, S_a3Reaching ZVS commutation condition, reducing the exciting current to zero at tC time; s_a3Conduction may be controlled between time period T9C;

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(t10-t 11): at time t10, 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; at time t11, the potential at point P rises to V_AUXDa1 is naturally turned on; 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_10-11\*MERGEFORMAT(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)<t 0): the circuit is in a steady state, S₁In a conducting state; load current I_LoadBy S₁Follow current, S_a1、S_a3Conducting, exciting current i L_mBy S_a1、S_a3Free flow of value of

Mode 2(t0-t 1): at time t0, turn off S_a3Commutation inductor L_rPassing through a transformer and an excitation inductor L_mAfter being connected in parallel with an auxiliary capacitor C_a3、C_a4Resonance occurs, R point potentialDropping, commutating inductive current

Increase from zero; excitation current

A positive change;

this mode S_a3Voltage v across_Sa3And primary winding current i_NThe expression is:

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 time t1, S_a3Voltage resonance at both ends to V_AUXThe time according to the present resonance mode is:

mode 3 (T1-T)₂): at the time of t1, the potential at the point R is reduced to 0, Da4 is naturally conducted, and S_a4The ZVS commutation condition is achieved, the voltage at two ends of the excitation inductor is opposite to the current direction, and the magnitude of the excitation 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_a4The conduction can be controlled to be ZVS conduction between the time period t 1-tA;

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\*MERGEFORMAT(70)

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 S₁Turn-off, commutation of the inductive current i_LrPart I of the medium excess load current_rDischarging the capacitor C2 and charging the capacitor C1, and enabling the potential of the point O to start to fall in a resonant mode;

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

wherein:

t₃at the moment, the potential of the point O is reduced to 0; the mode duration is:

wherein:

mode 5 (T)₃T4) at T₃At time, D2 turns on naturally, S₂Meeting ZVS commutation condition, commutating inductance current i L_rLinear droop, at time tB, commutating inductor current i L_rDown to load current i L oad, and main switch tube S₂May be in the time period T₃-tB;

thus, obtaining: the switching-on duration of the main switch ZVS is:

S₁turn off to S₂The on-time interval DN3 is:

the mode duration is:

S₂is conducted to S_a1The off-time interval DN4 is:

mode 6(t4-t6) turning off S at time t4_a1Commutating inductor current i L_rDown to 0A, excitation current i L_mIs increased reversely to

Excitation current

To C_a1Charging C_a2Discharging, and enabling the potential of the point Q to start to approximately linearly decrease; at the time of t5, the potential of the point Q is reduced to 0, and Da2 is naturally conducted; t5-t6 is determined by PWM control requirements, S_a2The conduction can be controlled between t5 and t 6;

t₄-t₅the duration is:

S_a1turn off to S_a2The on-time interval DN5 is:

DN5＝T_4-5\*MERGEFORMAT(83)

mode 7(t6-t8) time t6, turn off S₂Load current i_LoadC2 is charged, C1 is discharged, and the electric linearity of the point O is reduced; at time t7, the potential at point O rises to V_DCDiode D1 turns on naturally; t7-t8 is determined by PWM control requirements, S₁Conduction may be controlled after t 7;

t₆-t₇the duration is:

S₂turn off to S₁The on-time interval DN6 is:

DN6＝T_6-7\*MERGEFORMAT(85)

mode 8(t8-t9) time t8, turn off S_a4Exciting 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(t9-t10) when the potential at the point R rises to V at time t9_AUXDa3 is naturally turned on, S_a3Reaching ZVS commutation condition, reducing the exciting current to zero at tC time; s_a3Conduction may be controlled between time period T9C;

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(t10-t 11): at time t10, 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; at time t11, the potential at point P rises to V_AUXDa1 is naturally turned on; 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_10-11\*MERGEFORMAT(96)

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 design of the above parameters of each element is completed as follows (analysis is performed with the output current as positive time);

when V'_AUXLess than V_DC/2When the current is greater than the load current, S is turned off₂Ensuring 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 S₂Is in a satisfied formThe turn-off loss of the main switch is approximately negligible (turn-off loss less than 1/10):

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_2-3And S₁ZVT on time T_3BAfter 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;

in parallel, the following steps:

thus, obtaining:

wherein the value range of β obtained by the solution of sum is:

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

to ensure magnetizing current is in commutation inductor L_rAfter the linear discharge phase (t ═ t)₄) And resonant inductor L_rBefore the linear charging stage(t＝t₁) 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 is₁₄T is obtained by adding different time types₁-t₄Of each switching cycle, thereby

Different; from the sum, it can be seen that when the load current is 0, according to S_a4Shortest ZVS time T_{1A_min}Calculated L_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_LoadSubstituting 0 for formula (II), and summing to obtain t₁-t₄The time interval of (c):

T₁₄＝T_{14_min}\*MERGEFORMAT(104)

simultaneous:

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

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