WO2016086460A1

WO2016086460A1 - Traction converter having divided voltage sampling circuit for bus voltage ground protection

Info

Publication number: WO2016086460A1
Application number: PCT/CN2014/094056
Authority: WO
Inventors: 高永军; 姬惠刚; 管俊青; 张瑞峰; 胡明庆; 丁巧娅; 刘荣; 伍益民
Original assignee: 永济新时速电机电器有限责任公司
Priority date: 2014-12-02
Filing date: 2014-12-17
Publication date: 2016-06-09
Also published as: CN105720830A

Abstract

A traction converter having a divided voltage sampling circuit for bus voltage ground protection comprises two four-quadrant rectifiers (1, 2) having parallel outputs, a bus voltage detection circuit (3), and two three-phase inverters (4, 5) having parallel inputs, wherein the four-quadrant rectifiers (1, 2), the bus voltage detection circuit (3) and the three-phase inverters (4, 5) are sequentially connected. The bus voltage detection circuit (3) comprises a voltage sensor, a capacitor (C1), and at least two resistors (R1, R2, R3). The at least two resistors (R1, R2, R3) are connected in series between a positive terminal (VDC+) and a negative terminal (VDC-) of a bus. The voltage sensor and the capacitor (C1) are connected in parallel to one resistor of the at least two resistors (R1, R2, R3), one terminal of parallel connection is connected to the negative terminal (VDC-) of the bus, and the other terminal of parallel connection is grounded. The resistance values of the multiple resistors are reasonably set, and the bus voltage can be directly obtained according to the voltage value detected by the voltage sensor connected in parallel to one of the resistors and the setting of the resistance values of the resistors, thereby ensuring safe and reliable bus voltage detection.

Description

Traction converter with busbar voltage grounding protection voltage sampling circuit

Technical field

The invention relates to the technical field of high-speed EMUs, in particular to a traction converter with a busbar voltage grounding protection voltage sampling circuit.

Background technique

High-speed EMU technology has developed rapidly in recent years, and traction converters are an important part of high-speed EMUs. The traction converter outputs three-phase alternating current to drive the traction motor in the high-speed EMU to drive the operation of the EMU.

The traction converter is generally composed of a rectifier, an inverter, and the like. The rectifier rectifies the input alternating current, and the inverter is used to convert the rectified direct current into alternating current to drive the traction motor. In addition, the bus voltage processing loop is an important link connecting the rectifier and the inverter. The measurement of the bus voltage is very important for the whole system.

At present, a main measurement method is to directly connect the two ends of the bus bar with a voltage sensor to directly measure the bus voltage. However, due to the large bus voltage on the converter, the direct measurement method has a significant impact on the safety and reliability of the voltage sensor.

Summary of the invention

In view of the above problems, the present invention provides a traction converter with a busbar voltage grounding protection voltage sampling circuit for realizing safe and reliable measurement of the bus voltage.

The invention provides a traction converter with a busbar voltage grounding protection voltage sampling circuit, comprising:

a first four-quadrant rectifier, a second four-quadrant rectifier, a bus voltage detecting circuit, a first three-phase inverter, and a second three-phase inverter sequentially connected;

The first four-quadrant rectifier and the second four-quadrant rectifier output are connected in parallel, and two output ends of the first four-quadrant rectifier are respectively connected to a positive terminal and a negative terminal of the bus bar, and two of the second four-quadrant rectifiers Output terminals are respectively connected to the positive end and the negative end of the bus bar;

The bus voltage detecting circuit includes a voltage sensor, a capacitor, and at least two resistors, At least two resistors are connected in series between the positive terminal and the negative terminal of the bus bar, and the voltage sensor, the capacitor and one of the at least two resistors are connected in parallel, and one end connected in parallel and a negative terminal of the bus bar Connected, the other end connected in parallel is grounded;

The first three-phase inverter and the second three-phase inverter are connected in parallel, and two input ends of the first three-phase inverter are respectively connected to a positive end and a negative end of the bus bar, respectively The three-phase output of the first three-phase inverter is connected to a corresponding three-phase input end of at least one traction motor, and the two input ends of the second three-phase inverter are respectively connected to the positive end of the bus and negative The three-phase output of the second three-phase inverter is connected to a corresponding three-phase input of at least one other traction motor.

The traction converter with the busbar voltage grounding protection voltage dividing sampling circuit provided by the invention comprises four output quadruple rectifiers connected in parallel, a bus voltage detecting circuit and two three-phase inverters connected in parallel. Wherein, the bus voltage detecting circuit comprises a voltage sensor, a capacitor and at least two resistors, the at least two resistors being connected in series between the positive terminal and the negative terminal of the bus bar, the voltage sensor, the capacitor and one of the at least two resistors Parallel, one end of the parallel connection is connected to the negative end of the busbar, and the other end of the parallel connection is grounded. The four-quadrant rectifier with two outputs connected in parallel can make the higher harmonics of the input current of the four-quadrant rectifier be shifted from each other, so that some harmonics in the harmonic content of the primary current of the transformer cancel each other out. By reasonably setting the resistance values of the above plurality of resistors, using the voltage values detected by the voltage sensors connected in parallel to one of the resistors, and the setting of the resistance values of the respective resistors, the bus voltage can be indirectly obtained to ensure the bus voltage detection. Safe and reliable.

DRAWINGS

1 is a schematic structural diagram of a circuit of a first embodiment of a traction converter with a busbar voltage grounding protection voltage dividing sampling circuit according to the present invention;

2 is a schematic diagram showing the circuit structure of a second embodiment of a traction converter with a busbar voltage grounding protection voltage dividing sampling circuit according to the present invention.

detailed description

The technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. It is a partial embodiment of the invention, and not all of the embodiments. based on All other embodiments obtained by those skilled in the art without creative efforts are within the scope of the present invention.

1 is a schematic diagram of a circuit structure of a first embodiment of a traction converter with a busbar voltage grounding protection voltage dividing sampling circuit according to the present invention. As shown in FIG. 1, the traction converter includes:

a first four-quadrant rectifier 1, a second four-quadrant rectifier 2, a bus voltage detecting circuit 3, a first three-phase inverter 4 and a second three-phase inverter 5;

For the first four-quadrant rectifier 1 and the second four-quadrant rectifier 2, the output of the first four-quadrant rectifier 1 and the second four-quadrant rectifier 2 are connected in parallel, and the two output ends of the first four-quadrant rectifier 1 are the first output terminal E1. And the second output terminal F1 is respectively connected to the positive terminal VDC+ and the negative terminal VDC- of the bus bar, and the two output ends of the second four-quadrant rectifier 2, that is, the first output terminal E2 and the second output terminal F2 are respectively connected to the bus bar. Positive terminal VDC+ and negative terminal VDC-. In addition, the first input terminal A3 and the second input terminal B3 of the first four-quadrant rectifier 1 are configured to receive input alternating current, and the first input terminal A4 and the second input terminal B4 of the second four-quadrant rectifier 2 are configured to receive another Input AC power. Among them, the AC frequency of these two inputs is 50Hz.

In this embodiment, a four-quadrant rectifier with two outputs connected in parallel is used to rectify the input current. By using a pulse width modulation technique to control the phase shift angle, the peaks and troughs of the input current higher harmonics of the two rectifiers are used. Just staggered so that the higher harmonics of the current can cancel each other out.

For the bus voltage detecting circuit 3, the bus voltage detecting circuit 3 includes a voltage sensor, a capacitor C1, and at least two resistors. The number of resistors is three, for example, a first resistor R1, a second resistor R2, and a third. a resistor R3, the first resistor R1, the second resistor R2 and the third resistor R3 are connected in series between a positive terminal VDC+ and a negative terminal VDC- of the bus bar, the voltage sensor, the capacitor C1 and The third resistor R3 is connected in parallel, and one end connected in parallel is connected to the negative terminal VDC- of the bus bar, and the other end connected in parallel is grounded. It should be noted that the number of the above-mentioned resistors may be, for example, two or four, which is not limited to the embodiment, and how many voltage-dividing resistors are set, and the configuration of each resistor value needs to be detected according to the bus voltage. The size and cost of the circuit and other factors are comprehensively determined.

In the example in which the resistance is three, the resistance values of the first resistor R1, the second resistor R2, and the third resistor R3 are preferably set to be the same, and the resistance value ranges from 40 kΩ to 60 kΩ, and the capacitance C1 is taken. The value is 0.2uF. However, it is worth noting that the resistance of each resistor can also be different. For example, the resistance value that can be set to a multiple relationship is not limited to this embodiment.

The value of the bus voltage is critical to the overall traction converter, which indirectly reflects the operating state of the four-quadrant rectifier and the three-phase inverter. The value of the bus voltage of the four-quadrant rectifier operating under different operating conditions is different. Since the controller of the four-quadrant rectifier is a closed-loop system, the four-quadrant rectifier can be operated normally without knowing the actual value of the bus voltage. When the traction motor is controlled, the three-phase inverter also needs to modulate the pulse width modulation (PWM) signal emitted by the known bus voltage to control the traction motor. Therefore, the detection of the bus voltage is very necessary. To this end, in the bus voltage detecting circuit provided in this embodiment, the voltage sensor is connected in parallel to one of the plurality of series resistors, and the resistor is connected in parallel by one of the plurality of resistors. The voltage value detected by the voltage sensor and the setting of the resistance value of each resistor can indirectly obtain the bus voltage to ensure the safety and reliability of the bus voltage detection.

For the first three-phase inverter 4 and the second three-phase inverter 5, the first three-phase inverter 4 and the second three-phase inverter 5 are input in parallel, the first three-phase inverter 4 The two input terminals, that is, the first input terminal A5 and the second input terminal B5 are respectively connected to the positive terminal VDC+ and the negative terminal VDC- of the bus bar, and the three-phase output terminal of the first three-phase inverter 4 is connected to at least one traction motor. Corresponding to the three-phase input terminal, the two input terminals of the second three-phase inverter 5, that is, the first input terminal A6 and the second input terminal B6 are respectively connected to the positive terminal VDC+ and the negative terminal VDC- of the bus bar, and second The three-phase output of the three-phase inverter 5 is connected to a corresponding three-phase input of at least one other traction motor.

In this embodiment, two input and parallel three-phase inverters are used to drive the traction motor, and the three-phase inverter controls the PWM modulation according to the bus voltage detected by the bus voltage detection circuit, thereby driving the traction motor more reasonably. .

The traction converter provided in this embodiment comprises a four-quadrant rectifier with two outputs connected in parallel, a bus voltage detection circuit and two three-phase inverters with parallel inputs. Wherein, the bus voltage detecting circuit comprises a voltage sensor, a capacitor and at least two resistors, the at least two resistors being connected in series between the positive terminal and the negative terminal of the bus bar, the voltage sensor, the capacitor and one of the at least two resistors Parallel, one end of the parallel connection is connected to the negative end of the busbar, and the other end of the parallel connection is grounded. The four-quadrant rectifier with two outputs connected in parallel can shift the higher harmonics of the input current of the four-quadrant rectifier from each other, and some of the harmonics of the current on the primary side of the transformer cancel each other out. By reasonably setting the resistance values of the above plurality of resistors, using one of the resistors connected in parallel The voltage value detected by the voltage sensor and the setting of the resistance value of each resistor can indirectly obtain the bus voltage to ensure the safety and reliability of the bus voltage detection.

2 is a schematic diagram of a circuit structure of a second embodiment of a traction converter with a busbar voltage grounding protection voltage dividing sampling circuit according to the present invention. As shown in FIG. 2, the traction converter is based on the embodiment shown in FIG. include:

Supporting capacitor 6, the supporting capacitor 6 is connected in parallel with the output of the bus voltage detecting circuit 3, and is connected between the positive terminal VDC+ and the negative terminal VDC- of the bus bar, and the supporting capacitor 6 is used for filtering the bus voltage. Ripple.

Further, the traction converter further includes: a first pre-charging circuit 7 and a second pre-charging circuit 8 for controlling a variation amplitude of the input current when the traction converter is initially powered up, so as to change the input current The amplitude is not too large to avoid damage to the device.

The input terminal A1 of the first pre-charging circuit 7 is connected to the secondary side output winding P1 of the traction transformer, and the output terminal B1 of the first pre-charging circuit 7 is connected to the first input terminal A3 of the first four-quadrant rectifier 1 The second input end B3 of the first four-quadrant rectifier 1 is connected to the secondary side output winding N1 of the traction transformer;

The input terminal A2 of the second pre-charging circuit 8 is connected to the secondary side output winding P2 of the traction transformer, and the output terminal B2 of the second pre-charging circuit 8 is connected to the first input terminal A4 of the second four-quadrant rectifier 2 The second input end of the second four-quadrant rectifier 2 is connected to the secondary side output winding N2 of the traction transformer of B4.

Specifically, the first pre-charging circuit 7 includes a first switch K1, a second switch K2 and a resistor R4, the second pre-charge circuit 8 includes a third switch K3;

The first switch K1 and the resistor R4 are connected in series and connected in parallel with the second switch K2.

In actual use, when the traction converter is powered up, the first switch K1 in the first pre-charging circuit 7 is closed, the second switch K2 is turned off, and the third switch K3 of the second pre-charging circuit 8 is turned off. The current reaches the first four-quadrant rectifier 1 through the resistor R4, so that the current variation amplitude (di/dt) at the start of power-on is not excessive, reducing the hazard to each device. After 3-10ms, the switch K1 is disconnected, and K2 and K3 are closed. The resistance R4 ranges from 10 Ω to 50 Ω.

Specifically, as shown in FIG. 2, the first four-quadrant rectifier 1 and the second four-quadrant rectifier 2 are respectively composed of eight insulated gate bipolar transistors (IGBTs), that is, the first four-quadrant rectifier 1 is composed of S1- The IGBT composition represented by S8, the second four-quadrant rectifier 2 is characterized by S9-S16 IGBT composition. Specifically, the emitter of S1 is coupled to the collector of S3, the emitter of S2 is coupled to the collector of S4, the emitter of S5 is coupled to the collector of S7, and the emitter of S6 is coupled to the emitter of S8. The collectors are connected together. Wherein, the emitters of S1 and S2 are connected together and connected to the first input terminal A3 of the first four-quadrant rectifier 1; the emitters of S5 and S6 are connected together, and the second input terminal B3 of the first four-quadrant rectifier 1 Connecting; the collectors of S1, S2, S5 and S6 are connected together and connected to the first output E1 of the first four-quadrant rectifier 1; the emitters of S3, S4, S7 and S8 are connected together and first The second output terminal F1 of the four-quadrant rectifier 1 is connected. Similarly, a similar connection relationship is also applicable to the second four-quadrant rectifier 2, and the specific connection relationship is as shown in FIG. 2 and will not be described again.

In this embodiment, the two-quadrant four-quadrant rectifier is used to perform rectification processing on the input current, and the phase shift angle is controlled by Pulse-Width Modulation (PWM) technology, and the inputs of the two rectifiers are used. The peaks and valleys of the current harmonics are exactly staggered, so that the higher harmonics of the current can cancel each other out. Specifically, in the electric traction AC drive system, since the switching frequency of the high-power switching device is relatively low, in order to increase the system capacity and reduce the harmonic content of the input current on the grid side, a multiplexing technique is usually employed for the rectifier. In this embodiment, a two-folded pulse rectifier, that is, two four-quadrant rectifiers, is used, and the triangular carrier phases of the two rectifiers are shifted from each other by a phase angle of π/2, and then the waveform generation method and carrier phase shift in the PWM technology are utilized. The stepped wave obtained by the phase shift superposition in the technology, so that the peaks and troughs of the input current higher harmonics of the two rectifiers are exactly shifted, so that some harmonics in the harmonic content of the primary current of the transformer cancel each other out.

More specifically, as shown in FIG. 2, in the traction converter of the present embodiment, the first three-phase inverter 4 and the second three-phase inverter 5 are respectively composed of six IGBTs, that is, the first three The phase inverter 4 is composed of S17-S22, and the second three-phase inverter 5 is composed of S23-S28. Wherein, for the first three-phase inverter 4, the emitter of S17 is connected to the collector of S20, the emitter of S18 is connected to the collector of S21, and the emitter of S19 is connected to the collector of S22. Together, the collectors of S17, S18 and S19 are connected together and connected to the first input terminal A5 of the first three-phase inverter 4, and the emitters of S20, S21 and S22 are connected together, and the first three The second input terminal B5 of the phase inverter 4 is connected. The emitters of S17, S18 and S19 are respectively the three-phase outputs of the first three-phase inverter 4, and are respectively connected to corresponding three-phase inputs of at least one traction motor.

Correspondingly, for the second three-phase inverter 5, the emitter of S23 is connected to the collector of S26. Together, the emitter of S24 is connected to the collector of S27, the emitter of S25 is connected to the collector of S28, the collectors of S23, S24 and S25 are connected together, and the second three-phase inverter is connected. The first input terminal A6 of 5 is connected, the emitters of S26, S27 and S28 are connected together and connected to the second input terminal B6 of the second three-phase inverter 5. The emitters of S23, S24 and S25 are respectively the three-phase outputs of the second three-phase inverter 5, and are respectively connected to corresponding three-phase inputs of at least one traction motor.

It is worth noting that, preferably, each three-phase inverter drives two traction motors, and two traction motors driven by each three-phase inverter are connected to one bogie of the motor car.

In this embodiment, two three-phase inverters are connected in parallel on the bus voltage, each three-phase inverter drives two traction motors, and two traction motors driven by one three-phase inverter are connected to a bogie of a motor car. on. Compared with the prior art solution, the bogie driving mode adopts a vehicle-controlled open-loop control mode, that is, an inverter drives four traction motor operating modes, and has better control performance and higher reliability.

In this embodiment, the traction converter main circuit includes two pre-charging circuits connected in sequence, two output quadruple-connected rectifiers, a bus voltage detecting circuit, a supporting capacitor, and two three-phase inverters connected in parallel. Wherein, the pre-charging circuit is used to control the variation amplitude of the input current when the traction converter is initially powered up, so that the variation of the current of the input rectifying circuit is not excessively large, which is beneficial to reducing damage to the components of the converter; A parallel four-quadrant rectifier, by using pulse width modulation technology to control the phase shift angle, can make the higher harmonics of the input current of the four-quadrant rectifier shift to each other, so that some harmonics in the harmonic content of the primary current of the transformer cancel each other out. The voltage sensor in the bus voltage detecting circuit is connected in parallel to one of the plurality of resistors connected between the bus voltages, and the bus voltage can be indirectly obtained to ensure the safe and reliable detection of the bus voltage; the supporting capacitor is used for filtering the bus voltage. The ripple makes the voltage of the input inverter more accurate and stable; the two inputs are connected in parallel for accurately controlling the voltage input to the bus voltage according to the measured bus voltage, and the AC power is accurately converted to drive the traction motor. Safe and reliable operation.

Finally, it should be noted that the above embodiments are merely illustrative of the technical solutions of the present invention, and are not intended to be limiting; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art will understand that The technical solutions described in the foregoing embodiments may be modified, or some or all of the technical features may be equivalently replaced; and the modifications or substitutions do not deviate from the technical solutions of the embodiments of the present invention. range.

Claims

A traction converter with a busbar voltage grounding protection voltage sampling circuit, comprising:

a first four-quadrant rectifier, a second four-quadrant rectifier, a bus voltage detecting circuit, a first three-phase inverter, and a second three-phase inverter sequentially connected;

The first four-quadrant rectifier and the second four-quadrant rectifier output are connected in parallel, and two output ends of the first four-quadrant rectifier are respectively connected to a positive terminal and a negative terminal of the bus bar, and two of the second four-quadrant rectifiers Output terminals are respectively connected to the positive end and the negative end of the bus bar;

The bus voltage detecting circuit includes a voltage sensor, a capacitor and at least two resistors, the at least two resistors being connected in series between a positive terminal and a negative terminal of the bus bar, the voltage sensor, the capacitor and the at least two One of the resistors is connected in parallel, one end connected in parallel is connected to the negative end of the bus bar, and the other end connected in parallel is grounded;

The first three-phase inverter and the second three-phase inverter are connected in parallel, and two input ends of the first three-phase inverter are respectively connected to a positive end and a negative end of the bus bar, respectively The three-phase output of the first three-phase inverter is connected to a corresponding three-phase input end of at least one traction motor, and the two input ends of the second three-phase inverter are respectively connected to the positive end of the bus and negative The three-phase output of the second three-phase inverter is connected to a corresponding three-phase input of at least one other traction motor.
The traction converter according to claim 1, wherein the number of the at least two resistors is specifically three, which are a first resistor, a second resistor, and a third resistor, respectively.
The traction converter according to claim 2, wherein the resistances of the first resistor, the second resistor, and the third resistor are the same.
The traction converter according to claim 3, wherein the first resistor, the second resistor, and the third resistor have a resistance ranging from 40 kΩ to 60 kΩ, and the value of the capacitor is 0.2uF.
The traction converter according to any one of claims 1 to 4, further comprising: a supporting capacitor connected in parallel with an output of the bus voltage detecting circuit and connected to the bus bar Between the positive terminal and the negative terminal, the supporting capacitor is used to filter out ripple in the bus voltage.
The traction converter according to any one of claims 1 to 4, further comprising: a first pre-charging circuit and a second pre-charging circuit for initializing in the traction converter Control the variation of the input current during power-on;

An input end of the first pre-charging circuit is connected to a secondary side output winding P1 of the traction transformer, and an output end of the first pre-charging circuit is connected to a first input end of the first four-quadrant rectifier, a second input end of the four quadrant rectifier is connected to the secondary side output winding N1 of the traction transformer;

An input end of the second pre-charging circuit is connected to a secondary side output winding P2 of the traction transformer, and an output end of the second pre-charging circuit is connected to a first input end of the second four-quadrant rectifier, A second input of the quadrupole quadrature rectifier is coupled to the secondary side output winding N2 of the traction transformer.
The traction converter according to claim 6, wherein the first pre-charging circuit comprises a first switch, a second switch and a fourth resistor, and the second pre-charging circuit comprises a third switch;

The first switch and the fourth resistor are connected in series and in parallel with the second switch.