阅读说明：本技术 一种新型的dsrd脉冲功率电路 (Novel DSRD pulse power circuit ) 是由 梁琳 皮意成 于 2020-04-05 设计创作，主要内容包括：本发明公开了一种新型的DSRD脉冲功率电路,属于脉冲功率领域。针对目前DSRD脉冲电路对触发开关在耐压与通流能力方面要求高,或者负载输出电压脉冲峰值调节方法单一,或者电路中使用的可饱和变压器、磁开关需要额外复位电路等缺陷。一方面,本发明使用了饱和变压器和磁开关,同时饱和变压器饱和时间不受DSRD正向时间要求的约束,因此电路对触发开关的工作参数要求大大降低,且不需要利用额外的复位电路对可饱和变压器与磁开关进行复位；另一方面,本发明同时利用电容与电感作为储能模块中的储能元件,实现了在不改变电源电压的前提下,对负载上的电压脉冲峰值进行调节。(The invention discloses a novel DSRD pulse power circuit, and belongs to the field of pulse power. The DSRD pulse circuit aims at the defects that the requirement on the withstand voltage and the current capacity of a trigger switch is high, or the load output voltage pulse peak value adjusting method is single, or a saturable transformer and a magnetic switch used in the circuit need an additional reset circuit and the like. On one hand, the invention uses the saturation transformer and the magnetic switch, and the saturation time of the saturation transformer is not restricted by the forward time requirement of the DSRD, so the requirement of the circuit on the working parameters of the trigger switch is greatly reduced, and the saturable transformer and the magnetic switch do not need to be reset by using an additional reset circuit; on the other hand, the invention simultaneously utilizes the capacitor and the inductor as energy storage elements in the energy storage module, thereby realizing the adjustment of the voltage pulse peak value on the load on the premise of not changing the power supply voltage.)

1. A novel DSRD pulse power circuit, comprising: energy storage module, saturable transformer Tr, first energy transfer module, second energy transfer module, third energy transfer module and magnetic switch MS₁DSRD and load R_load；

The energy storage module is used for charging the capacitor by using a direct-current voltage-stabilizing power supply and charging the inductor when the saturable transformer Tr is in a saturated state;

the first energy transfer module is used for transferring the energy stored by the capacitor and the inductor to the secondary side of the saturable transformer Tr when the saturable transformer Tr is in an unsaturated state again, and the saturable transformer Tr is used as a boosting transformer; after the energy transfer is finished, the saturable transformer Tr enters a saturation state again;

the second energy transfer module is used for magnetic switch MS₁When the DSRD is in an unsaturated state, enabling the DSRD to flow forward current;

the third energy transfer module is used for magnetic switch MS₁When entering a saturation state, enabling the DSRD to flow reverse current;

wherein a saturable transformer Tr and a magnetic switch MS₁The switching between the saturated state and the unsaturated state is automatically realized according to the working state of the circuit without using an additional reset circuit for resetting; the load R is realized by controlling the energy charging time of the inductor or controlling the voltage of the direct-current stabilized power supply_loadThe size of the pulse peak value of the output voltage is flexible and adjustable.

2. The DSRD pulse power circuit as claimed in claim 1, wherein said energy storage module comprises a DC regulated power supply, a first controllable switch S₁Fast recovery diode D₀And a first capacitor C₁A first energy storage module composed of a DC voltage-stabilized power supply and a first inductor L₁The second energy storage module is formed by sequentially connecting the primary side of the saturable transformer Tr; the first energy transfer module is composed of a first capacitor C₁A second controllable switch S₂First inductor L₁A saturable transformer Tr and a second capacitor C₂Forming; the second energy transfer module is composed of a second capacitor C₂A third inductor L3, a long reverse recovery time diode D₁A third capacitor C₃A second inductor L₂DSRD and saturable transformer Tr secondary side; the third energy transfer module is composed of a third capacitor C₃Magnetic switch MS₁DSRD and second inductor L₂Forming;

the first energy storage module is arranged at a first controllable switch S₁After the conduction, the first capacitor C is supplied by the DC stabilized voltage supply₁Charging;

the second energy storage module is arranged on the first controllable switch S₁After the saturable transformer Tr is turned on and enters a saturation state, a DC stabilized power supply supplies power to the first inductor L₁Charging;

the first energy transfer module is arranged on a first controllable switch S₁Off, second controllable switch S₂When the saturable transformer Tr is turned on and is in an unsaturated state again, the first capacitor C is connected₁First inductor L₁Is transferred to the second capacitor C₂After the energy transfer is finished, the saturable transformer Tr enters a saturation state again;

the second energy transfer module is opposite to the second capacitor C at the first energy transfer module₂At the end of the energy transfer, the second capacitor C₂A long reverse recovery time diode D through a third inductor L3₁A third capacitor C₃A second inductor L₂DSRD and secondary side of saturable transformer Tr to transfer energy to third capacitor C₃During the period DSRD, a forward current flows;

the third energy transfer module is used for transferring a third capacitor C to the second energy transfer module₃At the end of the energy transfer, the magnetic switch MS₁Entering a saturated state, the third capacitor C₃By magnetic switch MS₁DSRD and second inductor L₂Discharge energy is transferred to the second inductor L₂In the above period, a reverse current flows in the DSRD; wherein, the magnetic switch MS₁At the second capacitor C₂Enters a saturated state before being charged and is arranged in a third capacitor C₃Entering an unsaturated state again when charging;

when the third capacitor C₃When the voltage drops to 0V, DSRD enters the blocking state rapidly, and the second inductor L₂The current on the load is rapidly transferred to the load R_loadAt the load R_loadGenerating a voltage pulse;

by controlling the first controllable switch S₁To control the firstInductor L₁The stored energy or the voltage of the DC stabilized power supply is controlled to control the first capacitor C₁And a first inductor L₁To realize a load R_loadThe size of the output voltage pulse peak is flexible and adjustable;

saturable transformer Tr and magnetic switch MS₁The switching between the saturated state and the unsaturated state is automatically realized according to the working state of the circuit, and an additional reset circuit is not needed for resetting.

3. The novel DSRD pulsed power circuit of claim 1 or 2, wherein the DSRD is a SiDSRD or a SiC DSRD.

4. The novel DSRD pulse power circuit of claim 1 or 2, wherein said regulated DC power supply is composed of a common regulated DC power supply and a capacitor connected in parallel.

5. The DSRD pulse power circuit of claim 2, wherein said fast recovery diode D₀The reverse recovery time is within 100 ns.

6. The novel DSRD pulsed power circuit of claim 2, wherein said long reverse recovery time diode D₁Is longer than the second capacitance C₂A long reverse recovery time diode D through a third inductor L3₁A third capacitor C₃A second inductor L₂DSRD and secondary side of saturable transformer Tr are discharged to transfer energy to third capacitor C₃Time of (d).

7. The DSRD pulse power circuit as claimed in claim 2 or 6, wherein said first capacitor C₁A second capacitor C₂Satisfies the relationship:

wherein n is the turn ratio of the primary side and the secondary side of the saturable transformer Tr.

8. The DSRD pulse power circuit as claimed in claim 6 or 7, wherein the second capacitor C₂A third capacitor C₃A third inductor L₃And a second inductor L₂The following relationship is satisfied:

the unit of T is ns, when the circuit uses Si DSRD, T ∈ [70,150], the unit is ns, when the circuit uses SiC DSRD, T is less than or equal to 70.

Technical Field

The invention belongs to the technical field of pulse power, and particularly relates to a novel DSRD pulse power circuit.

Background

The pulse power technology is an electro-physical technology which stores energy within a relatively long time and releases the stored energy to a load within a short time through a switching device to generate high-power electric pulses, and is widely applied to the fields of high-power microwaves, nuclear physical technologies, sewage purification and the like.

In pulse power systems, gas and liquid switches are generally used, such as spark gap, thyristor and oil-immersed switches, which have high withstand voltage and high throughflow, but are unstable, have a low lifetime and a low operating frequency. With the rapid development of semiconductor switches in recent years, more and more semiconductor switches are applied to pulse power applications such as thyristors in power electronics, insulated gate bipolar transistors. These switches have high operating frequency, stable operation and long service life, but have weak voltage resistance and low current capacity.

In order to adapt to the development of pulse power technology, pulse power technology semiconductor devices specifically applied to pulse power technology are also being further researched, for example: RSD (reverse switching transistor), RBDT (reverse blocking Diode Thyristor), DSRD (Drift Step Recovery Diode), and the like. DSRD belongs to an open circuit type semiconductor switch specially applied to the field of pulse power, the structure of the switch is similar to that of a PIN diode, the switch is a P + -P-N-N + type four-layer structure, and ultrashort reverse recovery time is achieved. The specific working principle of the DSRD is that in an initial state, a forward bias current is provided for the DSRD, the duration is controlled within a certain range, a thin unbalanced plasma layer with high density is formed near a PN junction, a reverse voltage is applied to the DSRD, due to the existence of the unbalanced plasma layer, a reverse current flows through the DSRD, when the charge quantity flowing in the reverse direction of the DSRD is the same as the charge quantity flowing in the forward direction, the DSRD enters a blocking state rapidly, and the conversion time is generally several nanoseconds. In practice, dsred is typically used in combination with an inductor to form a voltage pulse across the load, the pulse width of the voltage pulse being on the order of nanoseconds.

Existing DSRD pulse circuits can be divided into two main categories, the first category is a pulse circuit with initial energy in an inductor, and the structure is shown in figure 1; the second type is a pulse circuit with initial energy in a capacitor, and the structure is shown in FIG. 2. The DSRD pulse circuit of the first type can not output voltage pulses with larger peak values, and the DSRD pulse circuit of the second type can output voltage pulses with larger peak values, but can not flexibly adjust the peak values of the output voltage pulses.

Disclosure of Invention

In view of the above defects or improvement needs in the prior art, the present invention provides a novel DSRD pulse power circuit, which aims to solve the technical problems that the peak value of the voltage pulse output by the current DSRD pulse circuit is not easy to adjust, and the requirement on the working parameter of the trigger switch is high when the voltage pulse with the high voltage peak value is output.

To achieve the above object, the present invention provides a novel DSRD pulse power circuit, comprising: energy storage module, saturable transformer Tr, first energy transfer module, second energy transfer module, third energy transfer module and magnetic switch MS₁DSRD and load R_load；

The energy storage module is used for charging the capacitor by using a direct-current voltage-stabilizing power supply and charging the inductor when the saturable transformer Tr is in a saturated state;

the first energy transfer module is used for transferring the energy stored by the capacitor and the inductor to the secondary side of the saturable transformer Tr when the saturable transformer Tr is in an unsaturated state again, and the saturable transformer Tr is used as a boosting transformer; after the energy transfer is finished, the saturable transformer Tr enters a saturation state again;

the second energy transfer module is used for magnetic switch MS₁When the DSRD is in an unsaturated state, enabling the DSRD to flow forward current;

the third energy transfer module is used for magnetic switch MS₁When entering a saturation state, enabling the DSRD to flow reverse current;

wherein a saturable transformer Tr and a magnetic switch MS₁The switching between the saturated state and the unsaturated state is automatically realized according to the working state of the circuit without using an additional reset circuit for resetting; the load R is realized by controlling the energy charging time of the inductor or controlling the voltage of the direct-current stabilized power supply_loadThe size of the pulse peak value of the output voltage is flexible and adjustable.

Based on the technical characteristics, the invention has the beneficial effects that: on one hand, the circuit uses the saturation transformer and the magnetic switch, and can output high-peak voltage pulse even under the condition of small input voltage, so that the requirement of the circuit on the working parameters of the trigger switch is greatly reduced, and the saturable transformer and the magnetic switch are not required to be reset by using an additional reset circuit; on the other hand, the voltage pulse peak value on the load can be adjusted on the premise of not changing the power supply voltage, the voltage pulse peak value on the load can also be adjusted by adjusting the power supply voltage, and the adjusting mode is flexible.

Further, the energy storage module comprises a direct current stabilized power supply and a first controllable switch S₁Fast recovery diode D₀And a first capacitor C₁A first energy storage module composed of a DC voltage-stabilized power supply and a first inductor L₁The second energy storage module is formed by sequentially connecting the primary side of the saturable transformer Tr; the first energy transfer module is composed of a first capacitor C₁A second controllable switch S₂First inductor L₁A saturable transformer Tr and a second capacitor C₂Forming; the second energy transfer module is composed of a second capacitor C₂A third inductor L₃Long reverse recovery time diode D₁A third capacitor C₃A second inductor L₂DSRD and saturable transformer Tr secondary side; the third energy transfer module is composed of a third capacitor C₃Magnetic switch MS₁DSRD and second inductor L₂Forming;

the first energy storage module is arranged at a first controllable switch S₁After the conduction, the first capacitor C is supplied by the DC stabilized voltage supply₁Charging;

the second energy storage module is arranged on the first controllable switch S₁After the saturable transformer Tr is turned on and enters a saturation state, a DC stabilized power supply supplies power to the first inductor L₁Charging;

the first energy transfer module is arranged on a first controllable switch S₁Off, second controllable switch S₂When the saturable transformer Tr is turned on and is in an unsaturated state again, the first capacitor C is connected₁First inductor L₁In the energy transferTo the second capacitor C₂After the energy transfer is finished, the saturable transformer Tr enters a saturation state again;

the second energy transfer module is opposite to the second capacitor C at the first energy transfer module₂At the end of the energy transfer, the second capacitor C₂Through the third inductor L₃Long reverse recovery time diode D₁A third capacitor C₃A second inductor L₂DSRD and secondary side of saturable transformer Tr to transfer energy to third capacitor C₃During the period DSRD, a forward current flows;

the third energy transfer module is used for transferring a third capacitor C to the second energy transfer module₃At the end of the energy transfer, the magnetic switch MS₁Entering a saturated state, the third capacitor C₃By magnetic switch MS₁DSRD and second inductor L₂Discharge energy is transferred to the second inductor L₂In the above period, a reverse current flows in the DSRD; wherein, the magnetic switch MS₁At the second capacitor C₂Enters a saturated state before being charged and is arranged in a third capacitor C₃Entering an unsaturated state again when charging;

when the third capacitor C₃When the voltage drops to 0V, DSRD enters the blocking state rapidly, and the second inductor L₂The current on the load is rapidly transferred to the load R_loadAt the load R_loadGenerating a voltage pulse;

by controlling the first controllable switch S₁To control the on-time of the first inductor L₁The stored energy or the voltage of the DC stabilized power supply is controlled to control the first capacitor C₁And a first inductor L₁To realize a load R_loadThe size of the output voltage pulse peak is flexible and adjustable;

saturable transformer Tr and magnetic switch MS₁The switching between the saturated state and the unsaturated state is automatically realized according to the working state of the circuit, and an additional reset circuit is not needed for resetting.

Further, the DSRD is Si DSRD or SiC DSRD.

Further, when the common direct current stabilized power supply cannot output a large current, the common direct current stabilized power supply can be equivalent to the direct current stabilized power supply in a way of connecting a large capacitor in parallel. Correspondingly, the direct current stabilized voltage power supply has the beneficial effects that the cost of the common direct current stabilized voltage power supply capable of outputting larger current is higher, so that the cost of the pulse circuit can be lower by the equivalent method.

Further, the fast recovery diode D₀The reverse recovery time is within 100ns, such as a schottky SiC diode. Correspondingly, the diode D has the beneficial effects₀The reverse recovery process will result in a first capacitance C₁For the first inductor L₁Discharge, thereby failing to control the first capacitor C₁Diode D with small upper voltage and reverse recovery time₀Can ensure C₁After the charging is completed, the voltage remains stable, so that the peak magnitude of the voltage pulse on the load can be accurately controlled.

Further, the long reverse recovery time diode D₁Is longer than the second capacitance C₂Through the third inductor L₃Long reverse recovery time diode D₁A third capacitor C₃A second inductor L₂DSRD and secondary side of saturable transformer Tr are discharged to transfer energy to third capacitor C₃Time of (d). Correspondingly, the beneficial effects are that₁If the reverse recovery time is less than C₂By D₁、L₃、C₃、L₂DSRD and Tr discharge to transfer energy to a capacitor C₃Time of (1), then C₂Cannot be completely transferred to C₃This may result in unnecessary energy loss, reducing the operating efficiency of the pulse circuit.

Further, the first capacitor C₁A second capacitor C₂Satisfies the relationship:

wherein n is the turn ratio of the primary side and the secondary side of the saturable transformer Tr. Correspondingly, the beneficial effect is that the relation can ensure C₁The energy is completely transferred to the capacitor C through the saturable transformer Tr₂Therefore, the pulse circuit can have higher working efficiency.

Further, a second capacitor C₂A third capacitor C₃A third inductor L₃And a second inductor L₂The following relationship is satisfied:

t can determine the conduction time of the forward current of the DSRD, when the circuit uses Si DSRD, T belongs to 70ns-150 ns; when the circuit uses SiC DSRD, T is within 70 ns. Correspondingly, the beneficial effect is that the relation can ensure C₂The energy on the capacitor C is completely transferred to₃Meanwhile, the DSRD can be ensured to normally work so as to ensure that the pulse circuit has higher working efficiency.

In general, the above technical solutions contemplated by the present invention can achieve the following advantageous effects compared to the prior art.

The DSRD pulse circuit provided by the invention uses the capacitor and the inductor as an initial energy storage element at the same time, and can flexibly adjust the pulse peak value of the output voltage by adjusting the power supply voltage or the energy stored in the inductor; the circuit uses the saturation transformer and the magnetic switch, and can output high-peak voltage pulse even under the condition of small input voltage, so that the requirement of the circuit on the working parameters of the trigger switch is greatly reduced, and the saturable transformer and the magnetic switch are not required to be reset by using an additional reset circuit.

Drawings

FIG. 1 is a schematic circuit diagram of a pulse power circuit with initial energy in an inductor according to an embodiment of the present invention;

FIG. 2 is a schematic circuit diagram of a pulse power circuit with initial energy in a capacitor according to an embodiment of the present invention;

figure 3 is a schematic diagram of a novel DSRD pulse power circuit provided by an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

The invention provides a novel DSRD pulse power circuit, comprising: energy storage module, saturable transformer Tr, first energy transfer module, second energy transfer module, third energy transfer module and magnetic switch MS₁DSRD and load R_load(ii) a The energy storage module is used for charging the capacitor by using a direct-current voltage-stabilizing power supply and charging the inductor when the saturation transformer Tr is in a saturation state; the first energy transfer module transfers the energy stored by the capacitor and the inductor to the secondary side of the saturable transformer Tr when the saturable transformer Tr is in an unsaturated state again, and the saturable transformer Tr acts as a boosting transformer in the period; after the energy transfer is finished, the saturable transformer Tr enters a saturation state again; a second energy transfer module for use in the magnetic switch MS₁When the DSRD is in an unsaturated state, enabling the DSRD to flow forward current; a third energy transfer module for use in the magnetic switch MS₁When entering a saturation state, enabling the DSRD to flow reverse current; wherein a saturable transformer Tr and a magnetic switch MS₁The switching between the saturated state and the unsaturated state is automatically realized according to the working state of the circuit without using an additional reset circuit for resetting; the load R is realized by controlling the energy charging time of the inductor or controlling the voltage of the direct-current stabilized power supply_loadThe size of the pulse peak value of the output voltage is flexible and adjustable.

Specifically, as shown in fig. 3, the energy storage module comprises a regulated dc power supply, a first controllable switch S₁Fast recovery diode D₀And a first capacitor C₁A first energy storage module composed of a DC voltage-stabilized power supply and a first inductor L₁The second energy storage module is formed by sequentially connecting the primary side of the saturable transformer Tr; the first energy transfer module is composed of a first capacitor C₁A second controllable switch S₂First inductor L₁A saturable transformer Tr and a second capacitor C₂Forming; the second energy transfer module is composed of a second capacitor C₂A third inductor L₃Long reverse recovery time diode D₁A third capacitor C₃A second inductor L₂DSRD and saturable transformer Tr secondary side; the third energy transfer module is composed of a third capacitor C₃Magnetic switch MS₁DSRD and second inductor L₂Forming; a first energy storage module in the first controllable switch S₁After the conduction, the first capacitor C is supplied by the DC stabilized voltage supply₁Charging; a second energy storage module arranged on the first controllable switch S₁After the saturable transformer Tr is turned on and enters a saturation state, a DC stabilized power supply supplies power to the first inductor L₁Charging; a first energy transfer module in the first controllable switch S₁Off, second controllable switch S₂When the saturable transformer Tr is turned on and is in an unsaturated state again, the first capacitor C is connected₁First inductor L₁Is transferred to the second capacitor C₂After the energy transfer is finished, the saturable transformer Tr enters a saturation state again; a second energy transfer module for the second capacitor C₂At the end of the energy transfer, the second capacitor C₂Through the third inductor L₃Long reverse recovery time diode D₁A third capacitor C₃A second inductor L₂DSRD and secondary side of saturable transformer Tr to transfer energy to third capacitor C₃A forward current flows during the time period DSRD, wherein L₃The effects are that firstly, the current is limited, secondly, the duration time of the forward current of the DSRD is controlled, and the DSRD can be replaced by a resistor in application; a third energy transfer module for the third capacitor C₃At the end of the energy transfer, the magnetic switch MS₁Entering a saturated state, the third capacitor C₃By magnetic switch MS₁DSRD and second inductor L₂Discharge, transfer energy to the second powerFeeling L₂In the above period, a reverse current flows in the DSRD; wherein, the magnetic switch MS₁At the second capacitor C₂Enters a saturated state before being charged and is arranged in a third capacitor C₃Entering an unsaturated state again when charging;

when the third capacitor C₃When the voltage drops to 0V, DSRD enters the blocking state rapidly, and the second inductor L₂The current on the load is rapidly transferred to the load R_loadAt the load R_loadGenerating a voltage pulse;

by controlling the first controllable switch S₁To control the on-time of the first inductor L₁The charging time is further controlled by the energy stored in the controller or the voltage of the DC stabilized voltage supply is controlled to control the first capacitor C₁And a first inductor L₁To realize a load R_loadThe size of the output voltage pulse peak is flexible and adjustable; saturable transformer Tr and magnetic switch MS₁The switching between the saturated state and the unsaturated state is automatically realized according to the working state of the circuit, and an additional reset circuit is not needed for resetting.

To better explain the above pulse circuit, the embodiment of the present invention provides a set of parameters of each key element in the pulse circuit, which do not only satisfy the relationship required by the present invention, and each element parameter is C₁＝200nF，L₁400nH, the turn ratio of Tr is 10, C₂＝2nF，L₃＝400nH，D₁Has a reverse recovery time of 4 mus, C₃＝2nF，L₂＝12nH，R₁0.5 Ω. One operation of the circuit is as follows: 1) control S₁Turn on, DC initial time will be given to C₁Charging is carried out while a DC voltage is applied to the unsaturated Tr, and when the saturation transformer Tr is saturated, DC is supplied to L₁Charging; 2) switch off S₁Control switch S₂On, capacitance C₁And inductor L₁Resonance occurs, capacitance C₁The polarity of the voltage on the capacitor is changed; 3) due to the capacitance C₁The polarity of the voltage on the transformer is changed, the saturable transformer Tr is in an unsaturated state again, and the Tr can be regarded as a boosting transformer and the magnetic switch MS₁Has been previously in an unsaturated stateState, therefore most of C₁The voltage on the magnetic switch MS acts via Tr₁Up to magnetic switch MS₁Enters a saturation state and then the capacitor C₁Energy transfer to capacitor C via Tr₂(ii) a 4) At C₁Complete transfer of energy to the capacitor C₂At the time of, due to C₁Under the action of voltage, the saturable transformer Tr just enters a saturation state again, and Tr is equivalent to a short-circuit state; 5) due to MS₁At C₂Enters a saturated state before being charged, so when C is in₂Through L₃、D₁、C₃、L₂MS during DSRD discharge₁Re-entering unsaturated state, equivalent to open circuit state, C₂Transferring energy to C₃While the DSRD flows a forward current; 6) when C is present₂All of the energy on is transferred to C₃Time, magnetic switch MS₁In the capacitor C₃Just enters the saturation state again under the action of the upper voltage, which is equivalent to a short-circuit state C₃And L₂A resonance effect occurs, when a reverse current flows through the DSRD; 7) when C is present₂All of the energy is transferred to L₂When the amount of charge flowing in the reverse direction of the DSRD is exactly the same as the amount of charge flowing in the forward direction, the DSRD quickly enters a blocking state at L₂The energy on the upper side is rapidly transferred to R_loadThereby at R_loadForming a voltage pulse.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.