阅读说明：本技术 一种变压整流器输入功率控制电路 (Input power control circuit of transformer rectifier ) 是由 张海宝 于 2020-11-17 设计创作，主要内容包括：本发明公开了一种变压整流器输入功率控制电路,包括主变压器、辅助变压器、四个三相整流桥、控制电路；输入交流电源进入该电路后,首先进入主变压器的原边绕组,从主变压器绕组流出后再进入辅助变压器的输入端,主变压器副边的三角形绕组和星形绕组分别连接一个三相整流桥,辅助变压器副边的三角形绕组和星形绕组分别连接一个三相整流桥,辅助变压器副边连接的两个三相整流桥连接至控制电路,由控制电路检测输出电压的高低,控制电路的输出端连接至主变压器副边的两个三相整流桥的输出端,进行直流输出。本发明输入功率因数高、输入电流谐波含量低,输出电压稳定；由于输出电压为闭环控制,输出电压变化随输入电压变化调整率低。(The invention discloses an input power control circuit of a transformation rectifier, which comprises a main transformer, an auxiliary transformer, four three-phase rectifier bridges and a control circuit, wherein the main transformer is connected with the auxiliary transformer; the input alternating current power supply enters the circuit, firstly enters a primary winding of a main transformer, and then enters an input end of an auxiliary transformer after flowing out of the main transformer winding, a triangular winding and a star winding on a secondary side of the main transformer are respectively connected with a three-phase rectifier bridge, the triangular winding and the star winding on the secondary side of the auxiliary transformer are respectively connected with a three-phase rectifier bridge, two three-phase rectifier bridges connected with the secondary side of the auxiliary transformer are connected to a control circuit, the control circuit detects the level of output voltage, and the output end of the control circuit is connected to the output ends of the two three-phase rectifier bridges on the secondary side of the main transformer for direct current output. The invention has high input power factor, low harmonic content of input current and stable output voltage; because the output voltage is closed-loop control, the rate of adjustment of the change of the output voltage along with the change of the input voltage is low.)

1. The input power control circuit of the transformation rectifier is characterized by comprising a main transformer, an auxiliary transformer, four three-phase rectifier bridges and a control circuit; the input alternating current power supply enters the circuit, firstly enters a primary winding of a main transformer, and then enters an input end of an auxiliary transformer after flowing out of the main transformer winding, a triangular winding and a star winding on a secondary side of the main transformer are respectively connected with a three-phase rectifier bridge, the triangular winding and the star winding on the secondary side of the auxiliary transformer are respectively connected with a three-phase rectifier bridge, two three-phase rectifier bridges connected with the secondary side of the auxiliary transformer are connected to a control circuit, the control circuit detects the level of output voltage, and the output end of the control circuit is connected to the output ends of the two three-phase rectifier bridges on the secondary side of the main transformer for direct current output.

2. The input power control circuit of a transformer rectifier according to claim 1, wherein said primary side of said main transformer has three windings, the primary side winding of said auxiliary transformer is delta connected, the three input lines of said auxiliary transformer are connected to the output terminals of the three windings of said main transformer, and said main transformer and said auxiliary transformer are connected in series.

3. The transformer rectifier input power control circuit of claim 2, wherein the three windings of the primary side of the main transformer are independent of each other, and the six windings of the secondary side, wherein three of the secondary side windings are delta connected and the other three secondary side windings are star connected.

4. The transformer rectifier input power control circuit of claim 3, wherein the three windings of the primary side of the auxiliary transformer are delta connected and the six windings of the secondary side, wherein three of the secondary windings are delta connected and the other three secondary windings are star connected.

5. The transformer rectifier input power control circuit according to claim 4, wherein two ends of the three primary windings of the main transformer are respectively recorded as: a1 and a2, b1 and b2, c1 and c2, a1, b1 and c1 are connected with an external three-phase alternating current power supply, and a2, b3 and c4 are connected with three input ends of the primary side of the auxiliary transformer.

6. The input power control circuit of the transformer rectifier according to claim 5, wherein the delta winding and the star winding of the secondary side of the main transformer are respectively connected to a three-phase rectifier bridge, and the positive poles and the negative poles of the output ends of the two three-phase rectifier bridges are respectively connected together; the connection mode of the auxiliary winding of the auxiliary transformer is the same as that of the auxiliary winding of the main transformer, the anode of the auxiliary rectifier bridge of the auxiliary transformer is connected with the cathode of the auxiliary rectifier bridge of the main transformer, and is simultaneously connected with an inductor L1, the other end of the inductor L1 is connected with the D pole of a MOS tube V1 and the anode of a diode D1, the cathode of the diode D1 is connected with the anode of the auxiliary rectifier bridge of a main transformer T1, and the S pole of the MOS tube V1 is connected with the cathode of the auxiliary rectifier bridge of the auxiliary transformer T2.

7. The input power control circuit of the transformer rectifier according to claim 6, wherein the positive electrode of the secondary rectifier bridge output of the main transformer is connected to the control circuit as a feedback signal, the control circuit adjusts and controls the PWM signal duty ratio of the MOS transistor V1 according to the level of the feedback signal voltage, the level of the PWM signal duty ratio controls the current flowing through the secondary winding of the auxiliary transformer and the inductor L1, the current value on the secondary winding of the auxiliary transformer is proportional to the current value on the primary winding, the primary windings of the main transformer and the auxiliary transformer are connected in series, the control of the current on the primary winding of the main transformer is realized by controlling the on-duty ratio of the MOS transistor V1, the control of the input power of the main transformer T1 is further realized, and the closed-loop feedback of the output voltage is formed.

8. The input power control circuit of a transformer rectifier according to claim 7, wherein said main transformer is a three-phase six-winding transformer, the number of turns of the secondary winding is adjusted to equalize the line voltages between all the windings on the secondary winding, and the phase voltages generated by the delta-connected windings are 30 ° ahead of the phase voltages generated by the star-connected windings, and the vector phases of the output line voltages of the two sets of rectifier bridges are sequentially different by 30 °.

9. The transformer rectifier input power control circuit of claim 8, wherein the auxiliary transformer is a three-phase six-winding transformer, and the secondary side is connected in the same manner as the secondary side of the main transformer, but the primary side is connected in series with the primary side of the main transformer for controlling the loop impedance of the main transformer and thereby controlling the input current and the output current.

10. Use of a transformer rectifier input power control circuit according to any of claims 1-9 in the field of on-board transformer rectifiers.

Technical Field

The invention belongs to the technical field of airborne voltage transformation rectifiers, relates to an input power control circuit of a voltage transformation rectifier, and particularly relates to a control circuit for stabilizing output voltage of a multi-pulse voltage rectifier.

Background

In the current three-phase AC-DC rectification technology, the traditional uncontrollable or phased three-phase rectification circuit brings great harm to the airplane power grid and airborne electric equipment due to large harmonic content and low power factor, and the high power factor rectification scheme mainly comprises a three-phase PWM rectification technology, an active filtering technology, a step wave synthesis technology (zigzag transformer) and a multi-pulse rectification technology. Due to the high input power frequency (400Hz) of the onboard secondary power supply, the multi-pulse rectification technology is still not inferior in terms of volume and weight, and is obviously due to other technical solutions due to its strong overload capability and high reliability. Therefore, in order to reduce the harmonic content of the input current and improve the power factor, the multi-pulse rectification scheme is still the only technical scheme in the existing technical scheme of the airborne transformer rectifier.

However, the existing multi-pulse transformer rectifiers all have the problem of poor output voltage stability, when the output current is increased, the output voltage is reduced, and otherwise, the output voltage is increased, and particularly, the phenomenon is more obvious in some transformer rectifiers with large current output. The main reason for this problem is that the output voltage is controlled in an open loop, and when the output current increases, the voltage drop across the rectifier diode and the wire increases, resulting in a decrease in the final output voltage.

Disclosure of Invention

Objects of the invention

The purpose of the invention is: the input power control circuit of the transformer rectifier is provided, and the problem that the output voltage of the current airborne transformer rectifier is controlled in an open loop mode and is low in stability is solved.

(II) technical scheme

In order to solve the above technical problem, the present invention provides an input power control circuit of a transformer rectifier of the present invention, which comprises a main transformer T1, an auxiliary transformer T2, four three-phase rectifier bridges, and a control circuit; the input alternating current power supply enters the circuit, firstly enters a primary winding of a main transformer, and then enters an input end of an auxiliary transformer after flowing out of the main transformer winding, a triangular winding and a star winding on a secondary side of the main transformer are respectively connected with a three-phase rectifier bridge, the triangular winding and the star winding on the secondary side of the auxiliary transformer are respectively connected with a three-phase rectifier bridge, two three-phase rectifier bridges connected with the secondary side of the auxiliary transformer are connected to a control circuit, the control circuit detects the level of output voltage, and the output end of the control circuit is connected to the output ends of the two three-phase rectifier bridges on the secondary side of the main transformer for direct current output. The primary windings of the main transformer and the auxiliary transformer are all in triangular connection, and three input lines of the auxiliary transformer are respectively connected with the output ends of the three windings of the main transformer; the main transformer and the auxiliary transformer are in series connection, the current flowing through the main transformer can be changed by controlling the equivalent impedance of the auxiliary transformer, and the control of the secondary output current of the main transformer is further realized. The main transformer and the auxiliary transformer both adopt a 12-pulse voltage transformation rectification mode, so that the input power factor of the whole machine can be improved. The method for controlling the equivalent impedance of the auxiliary transformer is to control the output current of the secondary side of the auxiliary transformer, and in order to improve the conversion efficiency of the whole machine, the current output by the secondary side of the auxiliary transformer is transmitted to the secondary side of the main transformer through the BOOST circuit to be output as a part of energy output by the whole machine.

(III) advantageous effects

The input power control circuit of the transformer rectifier provided by the technical scheme can improve the stability of the output voltage of the 12-pulse transformer rectifier on the premise of ensuring high conversion efficiency, high power factor, lower input current harmonic content and the like.

Drawings

Fig. 1 is a schematic block diagram of a transformer rectifier input power control circuit of the present invention.

Fig. 2 is a specific circuit diagram of an input power control circuit of a transformer rectifier according to the present invention.

Detailed Description

In order to make the objects, contents, and advantages of the present invention clearer, the following detailed description of the embodiments of the present invention will be made in conjunction with the accompanying drawings and examples.

Although the conventional 12-pulse transformer rectifier can effectively reduce the harmonic content of the input current, the output voltage of the conventional 12-pulse transformer rectifier is reduced along with the increase of the output current, and the phenomenon is more serious particularly when the output current is larger. A circuit for realizing output voltage stabilization by regulating input current of a 12-pulse transformer rectifier is designed. When the output voltage is reduced, the input current of the transformer is forcibly increased through the control circuit, the output voltage is increased under the condition that the output load is not changed, and conversely, when the output voltage is increased, the input current of the transformer is forcibly reduced through the control circuit, and the output voltage is reduced under the condition that the output load is not changed.

FIG. 1 is a schematic block diagram of the present invention, in which the input power control circuit of the transformer rectifier of the present invention includes a main transformer T1, an auxiliary transformer T2, four three-phase rectifier bridges, and a control circuit; the input alternating current power supply enters the circuit, firstly enters a primary winding of a main transformer, and then enters an input end of an auxiliary transformer after flowing out of the main transformer winding, a triangular winding and a star winding on a secondary side of the main transformer are respectively connected with a three-phase rectifier bridge, the triangular winding and the star winding on the secondary side of the auxiliary transformer are respectively connected with a three-phase rectifier bridge, two three-phase rectifier bridges connected with the secondary side of the auxiliary transformer are connected to a control circuit, the control circuit detects the level of output voltage, and the output end of the control circuit is connected to the output ends of the two three-phase rectifier bridges on the secondary side of the main transformer for direct current output.

The primary windings of the main transformer and the auxiliary transformer are all in triangular connection, and three input lines of the auxiliary transformer are respectively connected with the output ends of the three windings of the main transformer;

the main transformer and the auxiliary transformer are in series connection, the current flowing through the main transformer can be changed by controlling the equivalent impedance of the auxiliary transformer, and the control of the secondary output current of the main transformer is further realized. The main transformer and the auxiliary transformer both adopt a 12-pulse voltage transformation rectification mode, so that the input power factor of the whole machine can be improved. The method for controlling the equivalent impedance of the auxiliary transformer is to control the output current of the secondary side of the auxiliary transformer, and in order to improve the conversion efficiency of the whole machine, the current output by the secondary side of the auxiliary transformer is transmitted to the secondary side of the main transformer through the BOOST circuit to be output as a part of energy output by the whole machine.

As shown in fig. 2, the components and connection relationship of the input power control circuit of the transformer rectifier of the present invention are as follows:

t1 is main transformer, T2 is auxiliary transformer. Three windings on the primary side of the main transformer T1 are independent of each other, six windings on the secondary side are independent of each other, three windings are connected in a delta mode, and the other three windings are connected in a star mode. Three windings on the primary side of the auxiliary transformer T2 are in delta connection, six windings on the secondary side are in delta connection, three windings are in delta connection, and the other three windings are in star connection. The primary side a1, b1 and c1 of the main transformer T1 are connected with an external three-phase alternating current power supply, and the primary side a2, b2 and c2 of the main transformer T2 are connected with three input ends. The triangular winding and the star winding on the secondary side of the main transformer T1 are respectively connected with a three-phase rectifier bridge, and the positive pole and the negative pole of the output ends of the two three-phase rectifier bridges are respectively connected together. The auxiliary winding of the auxiliary transformer T2 is connected in the same way as T1, and the positive pole of the auxiliary rectifier bridge of the auxiliary transformer T2 is connected with the negative pole of the auxiliary rectifier bridge of T1 and is connected with the inductor L1. The other end of the inductor L1 is connected to the D pole of the MOS transistor V1 and the anode of the diode D1, the cathode of the diode D1 is connected to the anode of the secondary rectifier bridge of the main transformer T1, and the S pole of the MOS transistor V1 is connected to the cathode of the secondary rectifier bridge of the auxiliary transformer T2. The positive electrode output by the secondary side rectifier bridge of the main transformer is used as a feedback signal to be connected into the control circuit, and the control circuit adjusts and controls the PWM signal duty ratio of the MOS tube V1 according to the level of the feedback signal voltage. The current flowing through the secondary winding of the auxiliary transformer T2 and the inductor L1 can be controlled by the duty ratio of the PWM signal, the current value on the secondary winding of the auxiliary transformer T2 is in equal proportion to the current value on the primary winding, and the primary winding of the main transformer T1 and the primary winding of the auxiliary transformer T2 are connected in series, so that the control on the current of the primary winding of the main transformer can be realized by controlling the duty ratio of the opening of the MOS tube V1, the control on the input power of the main transformer T1 is further realized, and the closed-loop feedback of the output voltage is formed.

The main transformer of the circuit utilizes a three-phase six-winding transformer, the primary side windings of which are in star connection, and the two secondary side windings of which are in triangle and star connection respectively to supply power for two groups of rectifier bridges respectively. The line voltages of all windings on the secondary side are equal by adjusting the number of turns of the windings on the secondary side, the phase voltage generated by the windings connected in a triangular mode is 30 degrees ahead of the phase voltage generated by the windings connected in a star mode, and the vector phases of the line voltages output by the two groups of rectifier bridges sequentially have a difference of 30 degrees. Because the output voltages of the two groups of rectifier bridges are equal, the rectified average voltage is also equal, and therefore the load can be supplied with power in parallel. The output parallel connection mode is suitable for the occasion of outputting large current.

The auxiliary transformer of the circuit also utilizes a three-phase six-winding transformer, the connection mode of the secondary side is the same as that of the main transformer, but the primary side of the auxiliary transformer is connected with the primary side of the main transformer in series to control the loop impedance of the main transformer and further control the input current and the output current.

The specific working principle is as follows: the main transformer rectifier and the auxiliary transformer respectively carry out 12-pulse transformation rectification, when the MOS tube V1 is completely closed, the output of the auxiliary transformer is unloaded, the equivalent impedance of the primary side of the auxiliary transformer is in the maximum state, and the output voltage of the main transformer is slightly lower than the set voltage. When the control circuit detects that the output voltage is lower than the set voltage, the duty ratio of the PWM signal of the control MOS tube V1 is increased, and the current flowing through the inductor L1 is increased. On the contrary, when the control circuit detects that the output voltage is higher than the set voltage, the duty ratio of the PWM signal of the control MOS transistor V1 is reduced, so that the current flowing through the inductor L1 is reduced

The detailed control process is as follows: when the current flowing through the inductor L1 gradually increases, the equivalent impedance of the primary side of the auxiliary transformer T2 decreases, and the current flowing through the primary side of the main transformer T1 further increases, and according to the magnetic coupling principle of the transformer, the current flowing through the secondary side of the main transformer T1 also increases in equal proportion. According to the formula of U ═ I × R (U is the output voltage, R is the equivalent resistance of the output terminal, and I is the current flowing through the secondary side of the main transformer T1), the magnitude of the current flowing through the secondary side of the main transformer T1 directly determines the magnitude of the output voltage. The control circuit regulates the secondary side current of the main transformer T1 by regulating the current flowing through the inductor L1. In addition, inductor L1 is used as an energy storage element according to the formula W1/2L I²(W is the energy stored in the inductor, L is the inductance, I is the current flowing through the inductor), the energy stored in the inductor is in direct proportion to the square of the current in the inductor, and when the MOS transistor V1 is turned off, the energy in the inductor is gradually released to the load (Ld and Rd) at the output end through the diode D1, so that the efficient utilization of the energy is realized.

According to the technical scheme, the invention has the following remarkable characteristics:

(1) high input power factor, low harmonic content of input current and stable output voltage.

(2) Because the output voltage is closed-loop control, the rate of adjustment of the change of the output voltage along with the change of the input voltage is low.

The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be regarded as the protection scope of the present invention.