CN-115940681-B - Novel dead zone self-adaptive control method and device for bridge arm topology

CN115940681BCN 115940681 BCN115940681 BCN 115940681BCN-115940681-B

Abstract

The invention provides a novel dead zone self-adaptive control method and device for bridge arm topology, which are used for reducing dead zone freewheel loss and effectively reducing a large number of harmonic waves caused by dead zone insertion by shortening a first dead zone time as much as possible on the premise of avoiding bridge arm straight-through during complementary driving, and improving the operation stability of an electric system. And, the second dead time is too large to affect the circuit output waveform quality, therefore, through adding the harmonic limit of the second dead time, the contradiction between efficiency and reliability is relieved.

Inventors

QIN HAIHONG
WANG LINGYAN
WANG WENLU
Peng Jiangjin
HAN XIANG
BU FEIFEI
CHEN ZHIHUI
ZHANG FANGHUA
ZHU CHUNLING
XU ZHENXIANG

Assignees

南京航空航天大学

Dates

Publication Date: 20260505
Application Date: 20220221

Claims (7)

1. The novel dead zone self-adaptive control method for the bridge arm topology comprises a bridge arm topology structure, a first power tube and a second power tube which are matched with each other, and is characterized in that dead zone time before opening a lower tube of a bridge arm is first dead zone time, and dead zone time after closing the lower tube of the bridge arm is second dead zone time; Determining the position of dead time according to the current flow direction, namely determining the optimal value of the first dead time according to the rising time of the grid source voltage of the first power tube and the falling time of the grid source voltage of the second power tube; step 2, fixing the first dead time as the optimal value of the first dead time in the full power range Optimizing the value of the second dead time based on the load current under different load conditions and the optimal value of the second dead time to obtain the optimized second dead time ; The optimal value of the second dead time is dynamically regulated by the load current and limited by the first dead time threshold value and the second dead time threshold value, the second dead time is optimally regulated, namely, when the load current is smaller than the first current threshold value, the second dead time is maintained to be the first dead time threshold value, when the load current is larger than the second current threshold value, the second dead time is maintained to be the second dead time threshold value, and when the load current is within the first current threshold value and the second current threshold value, the second dead time is controlled according to the formula As the load current increases and decreases, Q OSS (U DC ) is the amount of charge stored in the output capacitor of the power transistor when the drain-source voltage of the power transistor is U DC , R G is the drive resistor, C ISS is the input capacitor, U GS(off) is the drive off voltage, U GS(on) is the drive on voltage, U GS(th) is the threshold voltage, Is the load current; Step 3, defining the dead time before the second power tube is turned on as t d_on , the dead time after the second power tube is turned off as t d_off , judging the magnitude of the load current, and when the load current is greater than 0, making t d_on = ,t d_off = Otherwise let t d_on = ,t d_off = So as to realize the self-adaptive control of dead zones and minimize the total loss of bridge arm circuits.
2. The novel dead zone adaptive control method for bridge arm topology of claim 1, wherein the optimal value of the first dead zone time is: , Wherein t 2 is the time when the second power tube gate source voltage starts to drop to the threshold voltage, and t 2 is the time when the first power tube gate source voltage starts to rise to the threshold voltage.
3. The novel dead zone adaptive control method for bridge arm topology of claim 2, wherein the optimal value of the second dead zone time is: , Wherein t 4 is the time when the first power tube gate source voltage starts to drop to the second power tube drain source voltage drops to 0, and t 3 is the time when the second power tube gate source voltage starts to rise to the threshold voltage.
4. The novel dead zone adaptive control method for bridge arm topology of claim 1 or 3, wherein the optimized second dead zone time T D2_opt is specifically: , Wherein, the For load current, |i min | is the first dead band threshold I max is a first current threshold value limiting a second dead zone threshold value Q OSS (U DC ) is the amount of charge stored in the output capacitor of the power transistor when the drain-source voltage of the power transistor is U DC , R G is the driving resistor, C ISS is the input capacitor, U GS(off) is the driving off voltage, U GS(on) is the driving on voltage, and U GS(th) is the threshold voltage.
5. A novel dead zone adaptive control system for a bridge arm topology, characterized in that a novel dead zone adaptive control method for a bridge arm topology as claimed in claim 1 or 4 is implemented, the system comprising: The main power circuit consists of at least one pair of power tubes driven in a complementary mode; the driving circuit is used for driving the power tube in the main power circuit; and the controller is used for executing the novel dead zone self-adaptive control method for the bridge arm topology.
6. The novel dead zone adaptive control system for a bridge arm topology of claim 5, wherein the controller includes a current polarity determination module configured to determine whether current is flowing into or out of a bridge arm midpoint, thereby distinguishing a first dead zone time from a second dead zone time, determine that the current is in a positive direction when the current is flowing out of the bridge arm midpoint, and turn the current to be greater than zero when the current is flowing into the bridge arm midpoint, and determine that the current is in a negative direction when the current is flowing into the bridge arm midpoint, and turn the current to be less than zero.
7. The novel dead zone adaptive control system for a bridge arm topology of claim 6, wherein the upper bridge arm power tube and the lower bridge arm power tube are connected in series to form a bridge arm structure, In the module with the current larger than zero, the upper bridge arm power tube is an active power tube, the dead time position before the upper bridge arm power tube is turned on is determined to be a first dead time position, the dead time position after the upper bridge arm power tube is turned off is determined to be a second dead time position, the first dead time is controlled to be a fixed optimal value, the second dead time is controlled to dynamically change along with the load current, and the second dead time is limited by a first dead time threshold value and a second dead time threshold value; In the module with the current smaller than zero, the lower bridge arm power tube is an active power tube, the dead time position before the lower bridge arm power tube is turned on is determined to be a first dead time position, the dead time position after the lower bridge arm power tube is turned off is determined to be a second dead time position, the first dead time is controlled to be a fixed optimal value, the second dead time is controlled to dynamically change along with the load current, and the dead time is limited by a first dead time threshold value and a second dead time threshold value; The first dead zone threshold value is used for preventing serious waveform distortion of the bridge arm circuit output caused by overlarge dead zone time, and the second dead zone threshold value is used for reducing the operation complexity of a control program.

Description

Novel dead zone self-adaptive control method and device for bridge arm topology Technical Field The invention relates to the technical field of power electronics, in particular to a novel dead zone self-adaptive control method and device for bridge arm topology. Background In basic bridge arm topologies of common electrical systems, such as inverters, motor drives, etc., the bridge arm through problem is one of the most common and serious problems. Although the dead time is added to avoid bridge arm through as much as possible, the unreasonable dead time arrangement also has obvious negative effects on the electrical system. On one hand, dead time can cause output voltage and output current distortion of bridge arm circuits, increase total harmonic distortion rate, reduce electric energy conversion quality, and especially in high switching frequency occasions, larger output errors can be accumulated, so that the running stability of a motor system is affected. On the other hand, the reverse conduction loss of the power tube in the dead zone is high, and the system efficiency is obviously affected by the insertion of the dead zone time. In addition, the turn-off time of the power tube can be changed greatly along with the change of the output load current of the bridge arm circuit, when the dead time is too small, the unreleased energy of the output capacitor can be released through the channel of the power tube, so that the peak and loss of the channel current are caused, and the loss of the output capacitor is particularly serious under light load and high switching frequency. Therefore, excessive or short dead time causes additional power loss, which is detrimental to system efficiency improvement, and an effective dead time optimization setting method is currently needed to achieve the balance between high efficiency and high reliability. Disclosure of Invention Aiming at the problems that the reliability and the efficiency of a bridge arm circuit are greatly influenced by unmanageable dead zone setting, the existing dead zone optimization setting method still has the problems of insufficient excavation of the relation between dead zone time and load, increase of system volume and cost and the like, the invention provides a novel dead zone self-adaptive control method and device for bridge arm topology. The technical scheme of the invention is as follows: The novel dead zone self-adaptive control method for the bridge arm topology comprises a bridge arm topology structure, a first power tube and a second power tube which are matched with each other, and is characterized in that dead zone time before opening a lower tube of a bridge arm is first dead zone time, and dead zone time after closing the lower tube of the bridge arm is second dead zone time; Determining the position of dead time according to the current flow direction, namely determining the optimal value of the first dead time according to the rising time of the grid source voltage of the first power tube and the falling time of the grid source voltage of the second power tube; Step 2, fixing the first dead time as the optimal value T D1_opt of the first dead time in the full power range, and optimizing the value of the second dead time based on the load current under different load conditions and the optimal value of the second dead time to obtain the optimized second dead time T D2_opt; And 3, defining dead time before the second power tube is turned on as t d_on, expressing dead time after the second power tube is turned off as t d_off, judging the magnitude of load current, and when the load current is greater than 0, enabling t d_on＝TD1_opt,td_off＝TD2_opt, otherwise enabling t d_on＝TD2_opt,td_off＝TD1_opt to realize dead zone self-adaptive control so as to minimize total loss of a bridge arm circuit. The invention also discloses a novel dead zone self-adaptive control device for bridge arm topology, which comprises a main power circuit, a driving circuit and a control circuit, wherein the main power circuit consists of at least one pair of power tubes which are driven complementarily; and the controller is used for executing the novel dead zone self-adaptive control method. The current polarity judging module is used for judging whether the current flows into the middle point of the bridge arm or flows out of the middle point of the bridge arm so as to distinguish the first dead time from the second dead time, when the current is judged to flow out of the middle point of the bridge arm, the current is judged to be in a positive direction, the steering current is larger than zero, and when the current is judged to flow into the middle point of the bridge arm, the current is judged to be in a negative direction, and the steering current is smaller than zero. Further, in the module with the current larger than zero, the first dead time is the dead time before the upper pipe of the bridge arm is opened, the second dead time is the dead time aft