阅读说明：本技术 一种辅助变流器、单相整流器及其控制方法 (Auxiliary converter, single-phase rectifier and control method of single-phase rectifier ) 是由 王方 张军 窦蕴萍 宋春雨 李欣 于 2019-10-31 设计创作，主要内容包括：本发明公开一种辅助变流器、单相整流器及其控制方法；单相整流器包括：二极管单相桥,用于将交流输入电流整流为直流电流；二极管单相桥的输出连接到boost半桥的桥臂中点；boost半桥,boost半桥包括串联的一个快恢复二极管和一个全控型器件；用于将交流输入电流的波形控制为正弦；直流电容,与boost半桥并联；控制器,用于对交流输入电流和直流输出电压进行采样；并根据交流输入电流的采样值、直流输出电压的采样值和直流输出电压的给定值,计算出boost半桥的占空比,并转换成控制脉冲发送至boost半桥。采用本发明提供的方案,仅需一个全控的功率半导体器件,显著的少于传统的四象限整流器。(The invention discloses an auxiliary converter, a single-phase rectifier and a control method thereof; the single-phase rectifier includes: the diode single-phase bridge is used for rectifying the alternating current input current into direct current; the output of the diode single-phase bridge is connected to the middle point of a bridge arm of the boost half bridge; a boost half-bridge comprising a fast recovery diode and a fully controlled device in series; the control circuit is used for controlling the waveform of the alternating input current to be sine; the direct current capacitor is connected with the boost half bridge in parallel; a controller for sampling the AC input current and the DC output voltage; and according to the sampling value of the alternating current input current, the sampling value of the direct current output voltage and the given value of the direct current output voltage, calculating the duty ratio of the boost half bridge, converting the duty ratio into control pulses and sending the control pulses to the boost half bridge. By adopting the scheme provided by the invention, only one fully-controlled power semiconductor device is needed, and the number of the fully-controlled power semiconductor devices is obviously less than that of a traditional four-quadrant rectifier.)

1. A single-phase rectifier, comprising:

the diode single-phase bridge is used for rectifying the alternating current input current into direct current; the output of the diode single-phase bridge is connected to the middle point of a bridge arm of the boost half bridge;

the boost half bridge comprises a fast recovery diode and a fully controlled device which are connected in series; the control circuit is used for controlling the waveform of the alternating input current to be sine;

a DC capacitor connected in parallel with the boost half bridge;

and the controller is used for calculating the duty ratio of the boost half bridge according to the sampling value of the alternating current input current, the sampling value of the direct current output voltage and the given value of the direct current output voltage, converting the duty ratio into control pulses and sending the control pulses to the boost half bridge.

2. The single-phase rectifier of claim 1, further comprising:

the alternating current switch and the pre-charging device comprise a pre-charging branch circuit and a main power branch circuit which are connected in parallel;

the pre-charging branch comprises a pre-charging contactor and a pre-charging resistor which are connected in series; the pre-charging branch is used for pre-charging the direct current capacitor when the direct current capacitor is powered on for the first time so as to reduce starting current;

the main power branch is provided with a main contactor which is used for controlling an alternating current input end to be connected or not connected to the diode single-phase bridge; after the pre-charging branch finishes pre-charging, the main contactor is closed, and the pre-charging branch is bypassed; so that the ac input is connected to the midpoint of the legs of the diode single phase bridge.

3. The single-phase rectifier of claim 1,

when the fully-controlled device is closed, the direct current side of the diode single-phase bridge is short-circuited, and alternating current rises; when the fully-controlled device is switched off, the direct current side of the diode single-phase bridge discharges electricity to the direct current side through the fast recovery diode in the boost half bridge, and the alternating current drops.

4. The single-phase rectifier of claim 1 wherein the fully controlled devices are IGBT devices or MOSFET devices.

5. The single-phase rectifier of claim 1, comprising:

a plurality of boost half-bridges; the fully-controlled devices of the plurality of Boost half-bridges are connected in parallel; or the fully-controlled devices of the plurality of Boost half-bridges are conducted in a staggered mode.

6. The single-phase rectifier of claim 1, wherein the controller comprises:

the direct-current voltage closed-loop module is used for determining a current amplitude given value according to a sampling value of direct-current output voltage and a given value of the direct-current output voltage;

the catenary voltage phase observation module is used for determining the catenary voltage phase according to the duty ratio of the boost half bridge, the sampling value of the direct current output voltage and the sampling value of the alternating current input current;

the alternating current instruction generating unit is used for determining a current given value according to the current amplitude given value and the voltage phase of the overhead line system;

the alternating current closed-loop unit is used for determining a duty ratio according to the current given value and the sampling value of the alternating input current;

and the pulse generating unit is used for converting the duty ratio into a control pulse and sending the control pulse to the boost half bridge.

7. The single-phase rectifier of claim 6, wherein the catenary voltage phase observation module is configured to:

according to the duty cycle d, the DC voltage u_dcAnd the polarity of the alternating current i, calculating to obtain an input alternating voltage value u_in＝(1-d)*u_dc*sign(i)；

Calculating to obtain a network voltage value u of the secondary side according to the inductance L and the resistance R of the secondary side_net＝u_in+L*di/dt+R*i；

For u is paired_netPerforming integration;

phase locking is carried out through a phase-locked loop to obtain the voltage u of the contact network_netThe phase information θ of.

8. The single-phase rectifier of claim 6, further comprising:

the alternating current sensor is used for converting alternating input current and inputting the alternating input current to the controller; and

and the direct-current voltage sensor is used for converting the direct-current output voltage and inputting the direct-current output voltage to the controller.

9. A method of controlling a single phase rectifier according to any one of claims 1-8, comprising:

determining a current amplitude given value according to a sampling value of the direct-current output voltage of the single-phase rectifier and a given value of the direct-current output voltage;

determining the voltage phase of the contact network according to the duty ratio of a boost half bridge of the single-phase rectifier, the sampling value of the direct current output voltage and the sampling value of the alternating current input current;

determining a current given value according to the current amplitude given value and the voltage phase of the overhead line system;

determining a duty ratio according to the current given value and the sampling value of the alternating current input current;

converting the duty cycle into a control pulse and sending to the boost half bridge.

10. An auxiliary converter, comprising:

the single-phase rectifier of any one of claims 1-8;

and the input end of the three-phase inverter is connected with the direct current output end of the single-phase rectifier.

Technical Field

The invention relates to the field of rail transit vehicle-mounted equipment, in particular to an auxiliary converter, a single-phase rectifier and a control method of the auxiliary converter and the single-phase rectifier.

Background

Auxiliary converters are important onboard devices of rail vehicles (locomotives, motor cars) that provide three-phase ac power to auxiliary loads other than train traction. Fig. 1 shows a schematic representation of an auxiliary converter in a vehicle. Traditionally, a way of integrating the auxiliary winding in the traction transformer is used to supply the auxiliary converter. The auxiliary converter comprises a four-quadrant rectifier and a three-phase inverter. Fig. 2 shows a schematic diagram of a four-quadrant rectifier as used in the prior art.

The auxiliary converter in the mode has no working condition and needs the four-quadrant rectifier to work in an inversion state, namely the four-quadrant rectifier only works in the working condition that the power flows in a single direction. And thus is a waste of cost for an existing four-quadrant rectifier.

In addition, the control of the conventional auxiliary converter requires the use of phase information of the grid voltage, which also increases the complexity and the fault point of the auxiliary converter.

Disclosure of Invention

The present invention provides an auxiliary converter, a single-phase rectifier and a control method thereof, which are used for overcoming at least one problem in the prior art.

To achieve the above object, the present invention provides a single-phase rectifier, comprising: the diode single-phase bridge is used for rectifying the alternating current input current into direct current; the output of the diode single-phase bridge is connected to the middle point of a bridge arm of the boost half bridge; a boost half-bridge comprising a fast recovery diode and a fully controlled device in series; the control circuit is used for controlling the waveform of the alternating input current to be sine; a DC capacitor connected in parallel with the boost half bridge; a controller for sampling the AC input current and the DC output voltage; and according to the sampling value of the alternating current input current, the sampling value of the direct current output voltage and the given value of the direct current output voltage, calculating the duty ratio of the boost half bridge, converting the duty ratio into control pulses and sending the control pulses to the boost half bridge.

Optionally, the single-phase rectifier further comprises: the alternating current switch and the pre-charging device comprise a pre-charging branch and a main power branch which are connected in parallel; the pre-charging branch comprises a pre-charging contactor and a pre-charging resistor which are connected in series; the pre-charging branch is used for pre-charging the direct-current capacitor when the direct-current capacitor is powered on for the first time, so that starting current is reduced; the main power branch is provided with a main contactor for controlling the connection or disconnection of the alternating current input end to the diode single-phase bridge; when the pre-charging branch finishes pre-charging, the main contactor is closed, and the pre-charging branch is bypassed; so that the ac input is connected to the midpoint of the legs of the diode single phase bridge.

Optionally, when the fully-controlled device is closed, the direct current side of the diode single-phase bridge is short-circuited, and the alternating current rises; when the fully-controlled device is switched off, the direct current side of the diode single-phase bridge discharges electricity to the direct current side through the fast recovery diode in the boost half bridge, and the alternating current decreases.

Optionally, the fully controlled device is an IGBT device or a MOSFET device.

Optionally, the single-phase rectifier comprises: a plurality of boost half-bridges; the fully-controlled devices of the plurality of Boost half-bridges are connected in parallel; or the fully-controlled devices of a plurality of Boost half-bridges are conducted in a staggered mode.

Optionally, the controller comprises: the direct-current voltage closed-loop module is used for determining a current amplitude given value according to a sampling value of direct-current output voltage and a given value of the direct-current output voltage; the system comprises a contact network voltage phase observation module, a voltage phase observation module and a control module, wherein the contact network voltage phase observation module is used for determining the voltage phase of the contact network according to the duty ratio of a boost half bridge, the sampling value of direct current output voltage and the sampling value of alternating current input current; the alternating current instruction generating unit is used for determining a current given value according to the current amplitude given value and the voltage phase of the overhead line system; the alternating current closed-loop unit is used for determining the duty ratio according to the current given value and the sampling value of the alternating input current; and the pulse generating unit is used for converting the duty ratio into a control pulse and sending the control pulse to the boost half bridge.

Optionally, the catenary voltage phase observation module is configured to: according to the duty cycle d, the DC voltage u_dcAnd the polarity of the AC current i, calculating to obtain the input ACValue u of the current voltage_in＝(1-d)*u_dcSign (i); calculating to obtain a network voltage value u of the secondary side according to the inductance L and the resistance R of the secondary side_net＝u_in+ L di/dt + R i; for u is paired_netPerforming integration; phase locking is carried out through a phase-locked loop to obtain the voltage u of the contact network_netThe phase information θ of.

Optionally, the single-phase rectifier further comprises: the alternating current sensor is used for converting alternating input current and inputting the alternating input current to the controller; and the direct-current voltage sensor is used for converting the direct-current output voltage and inputting the direct-current output voltage to the controller.

In order to achieve the above object, the present invention further provides a control method of a single-phase rectifier, including: determining a current amplitude given value according to a sampling value of the direct current output voltage of the single-phase rectifier and a given value of the direct current output voltage; determining the voltage phase of the contact network according to the duty ratio of a boost half bridge of the single-phase rectifier, the sampling value of the direct current output voltage and the sampling value of the alternating current input current; determining a current given value according to the current amplitude given value and the voltage phase of the contact network; determining a duty ratio according to the current given value and a sampling value of the alternating input current; the duty cycle is converted to a control pulse and sent to the boost half bridge.

To achieve the above object, the present invention further provides an auxiliary converter, including: a single-phase rectifier; and the input end of the three-phase inverter is connected with the direct current output end of the single-phase rectifier.

The invention has the following beneficial effects: the main circuit of the rectifier only needs one fully-controlled power semiconductor device, and is obviously less than that of the traditional four-quadrant rectifier.

The adopted diode single-phase bridge does not need a fast recovery diode, only needs a common rectifier diode, and has obvious advantages in cost.

The single-phase rectifier control algorithm does not need contact network voltage information, and improves the reliability of the system.

According to the single-phase rectifier, the change rate of the alternating current can be controlled by controlling the on or off section of the full-control type device in the boost bridge arm, so that the waveform of the alternating current is close to sine and is in the same phase with the voltage waveform of a contact network.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 shows a schematic view of an auxiliary converter in a vehicle;

FIG. 2 shows a schematic diagram of a four-quadrant rectifier employed in the prior art;

fig. 3 shows a schematic connection of an auxiliary converter comprising a single-phase rectifier according to the invention;

FIG. 4 illustrates a schematic diagram of a single-phase rectifier according to an embodiment of the invention;

FIG. 5 shows a schematic structural diagram of a controller of an embodiment of the present invention;

fig. 6 shows a schematic structural diagram of a catenary voltage phase observation module according to an embodiment of the present invention;

fig. 7 shows a flowchart of a control method of the single-phase rectifier according to the embodiment of the invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without inventive effort based on the embodiments of the present invention, are within the scope of the present invention.

The invention provides a single-phase rectifier with a novel topology and a novel control method, which are used for an auxiliary converter in a rail transit vehicle.

Fig. 3 shows a schematic connection of an auxiliary converter comprising a single-phase rectifier according to the invention. As shown in fig. 3, the ac side of the single-phase rectifier of the present invention is connected to the auxiliary winding of the traction transformer, and the dc side is connected to the three-phase inverter in the auxiliary converter. The single-phase alternating current of the auxiliary winding of the traction transformer is converted into stable direct current to be supplied to a three-phase inverter, and meanwhile, the sine of the alternating input current waveform is controlled to be consistent with the power supply voltage waveform of a contact net, so that the power factor is close to 1.

Fig. 4 shows a schematic structural diagram of a single-phase rectifier according to an embodiment of the invention. As shown in fig. 4, the single-phase rectifier includes a diode single-phase bridge 5, a boost half-bridge 6, a dc capacitor 7, an ac switch and precharge device 12, a dc voltage sensor 8 and an ac current sensor 1, and a controller 11.

In the embodiment of the invention, an alternating current reactor is not required to be arranged in the single-phase rectifier, and the reactor required for working adopts the leakage reactance of the traction transformer, so that the integration degree of a system is improved, and the volume weight of the auxiliary converter is reduced.

The ac switching and pre-charging device 12 includes a pre-charging branch, a main power branch, in parallel. And a main contactor 4 is arranged on the main power branch circuit and used for controlling the connection or disconnection of the alternating current input end of the single-phase rectifier to the diode single-phase bridge. The pre-charging branch is formed by connecting a pre-charging contactor 2 and a pre-charging resistor 3 in series. When the power is powered on for the first time, the direct current capacitor 7 is precharged through the precharging branch circuit, the starting current is reduced, and the impact of the starting process on the whole device is also reduced. After the pre-charging is completed, the main contactor 4 is closed, and the pre-charging branch is bypassed. Two cables at the alternating current input end are connected to the middle point of a bridge arm of the diode single-phase bridge.

The diode single-phase bridge 5 is composed of four diodes, which may be a single diode or a plurality of diodes connected in parallel. The diode may be a common rectifying diode or a fast recovery diode. The diode single-phase bridge 5 rectifies the ac input of the single-phase rectifier into dc. The diode single-phase bridge 5 is connected to the bridge arm midpoint of the boost half-bridge 6.

The boost half-bridge 6 is formed by a fast recovery diode 9 and a fully controlled device 10. The single-phase rectifier may comprise only one boost half-bridge or may comprise a plurality of boost half-bridges connected in parallel. When a plurality of Boost half-bridges work together, the fully-controlled devices 10 can be connected in parallel or alternatively conducted, so that the equivalent switching frequency is improved. The fully controlled device 10 may be either an IGBT device or a MOSFET device. When the fully-controlled device 10 is closed, the direct current side of the diode single-phase bridge 5 is short-circuited, and the alternating current rises; when the fully controlled device 10 is switched off, the dc side of the diode single-phase bridge 5 discharges to the dc side through the fast recovery diode 9 in the boost half bridge, and the ac current drops. Therefore, by controlling the on and off of the fully controlled device 10, the rate of change of the alternating current can be controlled, and thus the waveform of the alternating current can be controlled to be sinusoidal.

The AC current sensor 1 and the DC voltage sensor 8 respectively convert the AC input current and the DC output voltage, and send the converted AC input current and DC output voltage to the controller for sampling and conversion, and the sampled and converted AC input current and DC output voltage are used as the input of a control algorithm.

A controller 11 for sampling the alternating current and the direct voltage and comprising a processor to implement a control algorithm. Specifically, the required duty ratio of the boost half-bridge can be calculated according to the sampling value and the control target (the given value of the dc output voltage), and then converted into the control pulse to be sent to the fully-controlled device 10.

The control algorithm of the invention is mainly characterized in that the alternating current instruction generation part is divided into amplitude value giving and phase position giving.

Amplitude given part: the amplitude of alternating current generated by the direct current voltage closed loop is given, a band elimination filter with twice contact network voltage frequency, namely a band elimination filter with 100Hz, can be added on a feedback channel of the direct current voltage, and the influence of direct current voltage low-frequency fluctuation in a single-phase rectifier on the given current amplitude is avoided.

Phase given part: the given phase of the current does not need to directly detect the voltage of a contact network; the input of the power grid voltage observation part is the duty ratio of a boost half bridge, alternating current and direct current voltage, the voltage of the contact network is estimated according to models of a traction transformer and a single-phase rectifier, and then phase information of the voltage of the contact network is obtained through a phase-locked loop and is used as the phase setting of the alternating current.

In the current closed loop part, the absolute value of the given value and the feedback value of the current is firstly taken, then the absolute value is used as the input of a current regulator after difference is made, the output of the current regulator is the given value of the duty ratio, and the control pulse of a boost half bridge is generated after pulse width modulation.

Fig. 5 shows a schematic structural diagram of a controller according to an embodiment of the present invention. As shown in fig. 5, the controller of the single-phase rectifier of the present invention includes a dc voltage closed-loop module, a catenary voltage phase observation module, an ac current instruction generation unit, an ac current closed-loop unit, and a pulse generation unit.

(1) The input of the direct current voltage closed loop module is a direct current voltage set value, and the direct current voltage is used as a feedback value after passing through the filter. And the given value of the direct current voltage and the feedback value of the direct current voltage are subjected to difference and then are sent to the regulator. The regulator may be a proportional integral regulator or a proportional integral derivative regulator. The filter of the direct current voltage can adopt a band elimination filter with twice voltage frequency of a contact network, namely a band elimination filter with 100Hz, so that the influence of the low-frequency fluctuation of the direct current voltage in the single-phase rectifier on the given current amplitude is avoided. And the output of the regulator in the direct-current voltage closed-loop module is the given value of the current amplitude.

(2) The input of the contact network voltage phase observation module is duty ratio, alternating current and direct current voltage u_dc. According to the duty cycle d, the DC voltage u_dcThe polarity of the AC current i, the input AC voltage value u can be calculated_in＝(1-d)*u_dcSign (i). Knowing the inductance L and the resistance R of the transformer converted to the secondary side, the network voltage value u of the secondary side can be calculated_net＝u_in+ L di/dt + R i. In order to avoid contact network voltage u_netDifferential calculation in the calculation process can be performed on u_netIntegrating, and then obtaining the voltage u of the contact network through a phase-locked loop_netThe phase information θ of. Fig. 6 shows a schematic structural diagram of the catenary voltage phase observation module according to the embodiment of the invention.

(3) An alternating current command generating unit for contactingNetwork voltage u_netThe phase information theta is subjected to sine operation and then multiplied by the given value of the current amplitude to obtain the given value of the current.

(4) And the alternating current closed-loop unit is used for taking absolute values of the given value of the current and the alternating current i at first, then taking the absolute values as the input of the current regulator after difference is made, and the output of the current regulator is the duty ratio.

(5) And the pulse generating unit is used for converting the duty ratio instruction into a square wave pulse with a certain switching frequency through pulse width modulation, and the square wave pulse is used as an instruction pulse of a full-control device of the boost half bridge.

The control algorithm can control the single-phase rectifier to convert the single-phase alternating current of the auxiliary winding of the traction transformer into stable direct current. And meanwhile, the sine of the waveform of the alternating input current is controlled and is consistent with the waveform of the power supply voltage of the contact network, so that the power factor is close to 1.

The invention has the following beneficial effects: the main circuit of the rectifier only needs one fully-controlled power semiconductor device, and is obviously less than that of the traditional four-quadrant rectifier.

The adopted diode single-phase bridge does not need a fast recovery diode, only needs a common rectifier diode, and has obvious advantages in cost.

According to the single-phase rectifier, the change rate of the alternating current can be controlled by controlling the on or off section of the full-control type device in the boost bridge arm, so that the waveform of the alternating current is close to sine and is in the same phase with the voltage waveform of a contact network.

Fig. 7 shows a flowchart of a control method of the single-phase rectifier according to the embodiment of the invention. As shown in fig. 7, the control method of the single-phase rectifier according to the embodiment of the present invention includes:

s701, determining a current amplitude given value according to a sampling value of direct current output voltage of the single-phase rectifier and a direct current voltage given value;

s702, determining a voltage phase of the overhead contact system according to the duty ratio of a boost half bridge of the single-phase rectifier, a sampling value of direct current output voltage and a sampling value of alternating current input current;

s703, determining a current given value according to the current amplitude given value and the voltage phase of the overhead line system;

s704, determining a duty ratio according to the current given value and the sampling value of the alternating current input current;

s705, the duty cycle is converted into a control pulse and sent to the boost half bridge.

The single-phase rectifier control algorithm does not need contact network voltage information, and improves the reliability of the system.

Those of ordinary skill in the art will understand that: the figures are merely schematic representations of one embodiment, and the blocks or flow diagrams in the figures are not necessarily required to practice the present invention.

Those of ordinary skill in the art will understand that: modules in the devices in the embodiments may be distributed in the devices in the embodiments according to the description of the embodiments, or may be located in one or more devices different from the embodiments with corresponding changes. The modules of the above embodiments may be combined into one module, or further split into multiple sub-modules.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.