CN201186619Y - Traction power supply equipment based on PWM rectifier - Google Patents

Abstract

The utility model discloses a traction power supply device based on a PWM rectifier. The device comprises: a transformer, a rectifier, a control board, a host computer and a switching power supply; Module, the control board uses CPLD for fault judgment and pulse blockade, and transmits 6 channels of PWM pulses through the optical fiber interface to drive the power switch tube in the PWM rectifier to work. The host computer is connected to the control board through Ethernet, and monitors and Fault diagnosis; the rectifier adopts the current decoupling control based on the synchronously rotating dq coordinate system, uses the phase-locked loop to obtain the synchronization angle of the grid voltage, and then performs PI adjustment on the d-axis current and the q-axis current respectively, and uses the method of space vector pulse width modulation Generate 6 PWM pulses.

Description

A traction power supply device based on PWM rectifier

technical field

The utility model belongs to the field of rail transit traction power supply, in particular to a traction power supply device based on a PWM rectifier.

Background technique

Urban rail transit is an important industry related to the national economy and the people's livelihood, and traction power supply to provide electric energy for urban rail transit is a vital link in this field. At present, urban rail transit mainly adopts 750V and 1500V DC power supply systems. Generally, 12-pulse or 24-pulse diodes are used for rectification. This kind of diode rectifier has been used for decades. Its biggest advantage is that the device has a simple structure and reliable performance, but it also has uncontrollable DC voltage and large voltage fluctuations. , The problem of large harmonic pollution to the AC power grid. In addition, because urban rail vehicles need frequent starting and braking, and when the vehicle starts quickly, the traction power required is large, and the DC voltage rectified by the diode will drop rapidly; when the vehicle is braking, in order to prevent the DC voltage from rising If the limit value is exceeded, the braking energy can only be consumed by a resistor, resulting in a great waste of energy. Therefore, it is of great significance to develop a traction power supply device with stable DC voltage, low harmonic pollution, and the ability to feed back braking energy to the AC grid.

Contents of the invention

The utility model proposes a traction power supply device based on a PWM rectifier (voltage type), the purpose of which is to provide a stable DC voltage for urban rail transit vehicles, which can feed back braking energy, has little harmonic pollution to the AC power grid, and has high reliability. Traction power supply to maximize energy saving and emission reduction.

The technical scheme of the utility model is as follows:

A traction power supply device based on a PWM rectifier, which is composed of five parts: a transformer, a PWM rectifier, a control board, a host computer, and a switching power supply. The primary side of the transformer is connected to the AC power grid, the secondary side is connected to the input terminal of the PWM rectifier, and the output of the PWM rectifier is connected to the DC catenary; the PWM rectifier is connected to the optical fiber interface circuit on the control board, and the control board detects the AC side and DC side of the PWM rectifier The corresponding voltage and current are controlled, and 6 PWM pulses are issued to drive the power switch tube in the PWM rectifier to work.

The PWM rectifier includes: an AC inductor, an AC filter capacitor, an intelligent power module, a fuse, a DC filter capacitor, A and B phase voltage sensors, a DC voltage sensor and a DC current sensor. Connections between the devices that make up the PWM rectifier:

Connect the A-phase voltage sensor and the B-phase voltage sensor to the transformer secondary side A and B phase respectively; the transformer secondary side is connected to the AC filter capacitor, and at the same time connect to one end of the AC filter inductor, and the other end of the AC filter inductor is respectively connected to three smart power At the midpoint of the module, the tops of the three intelligent power modules are connected together to one end of the fuse, and the other end of the fuse is connected to the positive end of the filter capacitor on the DC side, and a DC current sensor is installed on the positive end. The bottom ends of the three intelligent power modules are also And connected together to the negative terminal N of the DC support capacitor; a DC voltage sensor is connected between the positive terminal and the negative terminal N; the AC inductance, the AC filter capacitor and the leakage inductance of the grid side transformer form an asymmetrical T-shaped filter.

The control board includes: conditioning circuit, fault detection circuit, DSP, CPLD, memory, optical fiber interface circuit and Ethernet interface circuit. The specific connection relationship is: the input of the conditioning circuit is connected to the output of the sensor, the output of the conditioning circuit is connected to the DSP for sampling, and at the same time connected to the fault detection circuit, the output of the fault detection circuit is connected to the CPLD; the PWM port of the DSP is connected to the CPLD, and then connected to the optical fiber interface circuit through the CPLD ; In addition, the DSP is connected to the memory through the I2C bus; the data line, address line and read-write signal line of the DSP are connected to the Ethernet interface circuit.

Compared with the prior art, the utility model has the beneficial effects: (1) adopting PWM rectifier, the DC voltage is stable, the power factor is high, the harmonic pollution to the power grid is small, and the energy can flow in both directions, and the braking energy of the vehicle can be fed back Back to the AC power grid for other vehicles, and the energy saving effect is remarkable; (2) The power switching device in the main circuit adopts a high-power, highly integrated intelligent power module, which avoids the complicated circuit structure and driving circuit caused by the parallel connection of multiple low-power devices The main circuit structure and driving circuit are greatly simplified, and the reliability of the device is improved; (3) CPLD is used for fault judgment and pulse blockade, the control system is simplified, and the protection speed is fast; (4) Equipped with a special upper computer as the man-machine The interactive interface facilitates comprehensive real-time monitoring and fault diagnosis of the device.

Description of drawings

Figure 1 is a block diagram of the traction power supply device based on PWM rectifier

Figure 2 PWM rectifier main circuit

Figure 3 control board circuit

Figure 4 conditioning circuit

Figure 5 fault detection circuit

Figure 6 DSP circuit

Figure 7 CPLD circuit

Figure 8 Optical Fiber Interface Circuit

Figure 9 Ethernet interface circuit

Figure 10 memory circuit

Figure 11 Schematic diagram of voltage and current double closed-loop control based on synchronous rotating coordinate system

Figure 12 Schematic diagram of software phase-locked loop

Detailed ways

The traction power supply device described in this embodiment has a DC voltage of 750V and a power of 500kW.

The traction power supply device described in this embodiment, as shown in FIG. 1 , is composed of five parts: a transformer, a PWM rectifier, a control board, a host computer, and a switching power supply. The transformer is used for isolation and step-down, the primary side of the transformer is connected to the AC grid, and the secondary side is connected to the PWM rectifier; the PWM rectifier is used to realize AC/DC power conversion, and the DC output is connected to the DC catenary to provide DC power supply for rail transit vehicles; The control board completes the corresponding control by detecting the AC side voltage and current and the DC side voltage and current of the PWM rectifier, sends out 6 PWM drive pulses, drives the power switch tube in the PWM rectifier to work, and implements protection for the device at the same time; the host computer and the control board pass through Ethernet two-way connection, control the device, and display key variable waveforms, data storage and fault alarm.

The switching power supply in the traction power supply device is mainly used to supply power to the control board. The input 220V AC is converted into 5V, ±15V, 24V power supply for the control board. The switching power supply has stable output, small ripple and high reliability.

As shown in Fig. 2, the PWM rectifier in the traction power supply device includes: an AC inductor, an AC filter capacitor, an intelligent power module, a fuse, a DC filter capacitor, A and B phase voltage sensors, a DC voltage sensor and a DC current sensor. Connections between the devices that make up the PWM rectifier:

Connect A-phase voltage sensor 1 and B-phase voltage sensor 2 to the transformer secondary side A and B phase respectively; the transformer secondary side is connected to the AC filter capacitor 3, and at the same time connect to one end of the AC filter inductor 4, and the other end of the AC filter inductor 4 is respectively connected to To the midpoint of the three intelligent power modules 5, 6, and 7, the tops of the three intelligent power modules are connected together to one end of the fuse 8, and the other end of the fuse is connected to the positive terminal P of the filter capacitor 10 on the DC side, and the positive terminal P Install the DC current sensor 9 on the bottom of the three intelligent power modules and connect them together to the negative terminal N of the DC support capacitor C; connect the DC voltage sensor 11 between the positive terminal P and the negative terminal N; AC inductance 4, AC The filter capacitor 3 and the leakage inductance of the grid-side transformer form an asymmetric T-shaped filter. Compared with the traditional filter with only one inductance L, the order of the filter is higher, and the overall size of the filter is greatly reduced. It is mainly used for Filter out the switching frequency sub-harmonic current in the AC current to reduce the harmonic pollution to the power grid.

The transformer in the traction power supply device is an epoxy resin casting dry-type transformer, the primary side input voltage is 10kV, and it adopts star connection, which is convenient for grounding the high voltage side. The secondary side output voltage is 420V, also adopts star connection, and the transformer capacity is 500kVA.

The AC filter capacitor 3 is a non-polarized capacitor connected in a star shape, with a withstand voltage of 450VAC and a capacity of 150uF.

The intelligent power modules 5, 6, and 7 all adopt the SKiiP series intelligent IGBT power modules of Ximenkang Company, the parameters are 1700V/2400A, and the model is: SKiiP 2403GB173D. Each contains two upper and lower switching tubes, with its own heat sink, and each power module integrates drive, short circuit protection, current sensor, temperature sensor, and optical fiber interface. The power modules are connected through non-inductive busbars to reduce the influence of parasitic parameters on the main circuit. Each module can flow thousands of amperes of current, easy to use and high reliability. Since the current sensor is integrated inside the intelligent power module, the two-phase AC current _ia and _ib can be obtained without an external AC current sensor.

The fuse 8 is a 750V/1600A fast fuse from Ferraz Company, model: A75P1600-4. Its installation position is very special (between the power module and the DC support capacitor), so that it can protect when the power module is short-circuited or the DC output is short-circuited, preventing the expansion of the fault range.

The DC side filter capacitor 10 has a withstand voltage of 1200V and a capacity of 40000uF. It is a capacitor bank composed of multiple 400V withstand voltage electrolytic capacitors connected in series and parallel or multiple film capacitors connected in parallel. It is used to filter DC voltage ripple and stabilize DC voltage.

The A and B phase voltage sensors are used to measure the two-phase AC voltage u _a and u _b for AC overvoltage and undervoltage protection, and software phase-locked loop. The DC voltage sensor adopts the 1000V voltage sensor of LEM Company, the model is: AV100-1000; the DC current sensor adopts the 1000A current sensor of LEM Company, the model is LT1005-S.

The DC voltage sensor 11 is used to measure the DC voltage U _dc , perform closed-loop control, and stabilize the DC voltage.

The DC current sensor 9 is used for measuring the DC output current I _dc , calculating the output power of the power supply device and DC short circuit protection.

The upper computer communicates and exchanges data with the DSP in the control board through Ethernet. The upper computer adopts an industrial computer or a portable notebook computer, which can be used as a fixed system monitoring device and placed in the monitoring room of the power supply station; it can also be used for initial system debugging, recording and displaying key power waveforms, and improving debugging efficiency. The program in the upper computer is written in a high-level language to realize data storage, variable display, harmonic analysis, power calculation, and fault alarm functions.

Fig. 3 shows that the control board circuit in the traction power supply device includes: conditioning circuit, fault detection circuit, DSP, CPLD, memory, optical fiber interface circuit and Ethernet interface circuit.

The circuit of the control board is shown in Figure 3 to Figure 10, and the connection relationship between the components is as follows:

The ports Ua and Ia of the conditioning circuit are connected to the A-phase voltage sensor 1, the ports Ub and Ib are connected to the B-phase voltage sensor 2, the port Idc is connected to the DC current sensor 9, the port Udc is connected to the DC voltage sensor 11, and the ports Uai, Ubi, Iai, Ibi, Idci, Udci are respectively connected to the ports Uai, Ubi, Iai, Ibi, Idci, Udci of the fault detection circuit in sequence, and the ports ADUa, ADUb, ADIa, ADIb, ADIdc, ADUdc of the conditioning circuit are respectively connected to the ports of the DSP ADUa, ADUb, ADIa, ADIb, ADIdc, ADUdc are connected in sequence;

The ports DCOV, DCUV, ACUV, and ACOV of the fault detection circuit are respectively connected to the ports DCOV, DCUV, ACUV, and ACOV of the CPLD in sequence;

The ports PDNINT, PWM1, PWM2, PWM3, PWM4, PWM5, and PWM6 of the DSP are respectively connected to the ports PDNINT, PWM1, PWM2, PWM3, PWM4, PWM5, and PWM6 of the CPLD in sequence;

The ports XPWM1, XPWM2, XPWM3, XPWM4, XPWM5, and XPWM6 of the CPLD are respectively connected to the ports XPWM1, XPWM2, XPWM3, XPWM4, XPWM5, and XPWM6 of the fiber interface circuit in sequence; the ports of the fiber interface circuit are connected to the intelligent power module;

The ports ETH__/TEST, ETHBHEn, ETH__RST, ETI__ENn, ETH__IOR, ETH__IOW, XA1, XA2, XA3, XD0 to XD15 of the DSP are sequentially connected with the ports ETH__/TEST, ETHBHEn, TH__RST, ETH__ENn, ETH__IOR, ETH__IOW, XA1, XA2, XA3, XD1 to XD15 are connected, and the ports SCL and SDA of the DSP are respectively connected with the SCL and SDA of the memory.

In the control board, the conditioning circuit is used to filter the voltage and current signals from the sensors in the PWM rectifier, filter out high-frequency interference, and then convert the signal to within 0-3V, and then send it to DSP for AD sampling, and also send it to to the fault detection circuit; the fault detection circuit compares the voltage and current signals from the conditioning circuit with the set protection value, and sends the fault signal output from the comparison to the CPLD; the CPLD performs logical processing on all fault signals. If a serious fault occurs, Immediately block the pulse, and send an interrupt signal to the power protection interrupt port PDPINT of the DSP; the PWM pulse sent by the DSP is sent to the optical fiber interface circuit after passing through the CPLD, and then sent to each intelligent power module, so the CPLD can easily realize the function of hardware blocking the pulse; The memory is connected with the DSP through the SPI bus, and is used to permanently store some important operating parameters and system information, which will not be lost when power is off; the Ethernet interface circuit is connected with the DSP through data lines, address lines, and a small number of control lines for realizing High-speed data exchange with host computer.

Described DSP adopts 32 high-performance digital signal processors TMS320F2812 of TI Company, clock frequency 150M; Described CPLD is mainly used in logical protection and pulse blocking, adopts EMP3128A of Ateral Company; Mainly comprise a 10M in the described Ethernet interface circuit Ethernet control chip, signal CS8900A; the memory adopts non-volatile ferroelectric memory, the data will not be lost after power failure, and it uses SPI bus to exchange data with DSP, the model is: FM24CL64. DSP and CPLD adopt similar devices, both of which can achieve the beneficial effects of the utility model.

The upper computer in the traction power supply device adopts an industrial control computer, and the CPU adopts a dual-core high-performance processor to ensure the calculation speed; the network card adopts a 10M Ethernet card; a 160G large-capacity hard disk is configured to store the operating data of the power supply device in real time for future use Check; Use an uninterruptible power supply (UPS) to supply power to the host computer to ensure power supply safety.

The switching power supply in the traction power supply device adopts multiple switching power supply modules to provide 4 isolated stable DC voltages, including 1 channel of 5V, 1 channel of 15V, 1 channel of -15V, and 1 channel of 24V, with a total rated power of about 100W and an input of 220V The AC power comes from a UPS.

As mentioned above, a traction power supply device based on PWM rectifier, the PWM rectifier control adopts voltage and current double closed-loop control based on synchronous rotating coordinate system, as shown in Figure 4, where _ia and _ib are two-phase AC current, u _a and _ub are two-phase AC voltages.

The control method is shown in Figure 11, and its specific implementation steps are:

(1) Detect the two-phase AC voltage Ua and Ub, and use the phase-locked loop to obtain the grid voltage synchronization angle θ.

(2) Using the synchronous angle θ, the detected two-phase AC currents i _a and i _b are transformed into a synchronously rotating dq coordinate system to obtain d-axis current i _d and q-axis current i _q .

(3) Subtract the given value of DC voltage U _dc ^* from the actual detected DC voltage U _dc , and perform PI calculation to obtain the given value of d-axis current i _d ^* of the current loop, and the given value of q-axis current i _q ^* takes 0.

(4) Subtract the d-axis current given value _id ^* in (3) from the d-axis current _id in (2), and perform PI operation to obtain the d-axis control voltage V _d ; similarly, ( Subtract the q-axis current given value i _q ^* in (3) from the q-axis current i _q in (2), and perform PI operation to obtain the q-axis control voltage Uq.

(5) Transform V _d and V _q in (4) to the stationary coordinate system to obtain U _α and U _β .

(6) Use U _α and U _β to perform space voltage vector pulse width modulation (SVPWM) to obtain 6 PWM pulses.

The phase-locked loop adopts a software phase-locked loop, which uses the current synchronization angle to convert the grid voltage in the static coordinate system to the synchronous rotating coordinate system, and then sends the obtained q-axis voltage to the filter link to filter out high-frequency Interference, and then subtracted from the q-axis voltage given value 0 to perform PI control. The output of PI is the current angular frequency correction amount Δω, plus the power frequency angular frequency ω and then integrated to obtain the final grid voltage synchronization angle θ.

The PI control described above adopts an anti-saturation PI regulator.

Both the PI control of the voltage outer loop and the current inner loop adopt anti-saturation digital PI regulators.

In the above-mentioned control method, the phase-locked loop adopts a software phase-locked loop, and its principle is shown in Figure 12, which mainly includes four parts: coordinate transformation, filtering, PI adjustment, and integration. The working process of the phase locked loop is: using the current synchronous angle θ to convert the two-phase AC voltage u _a , u _b in the stationary coordinate system to the synchronous rotating coordinate system to obtain u _d , u _q , and then send the q-axis voltage u _q into the In the filtering link, after filtering out the high-frequency components introduced by grid voltage distortion or interference, the PI adjustment is performed after subtracting the given value of the q-axis voltage from zero. Integrate after the angular frequency ω, and finally get the corrected synchronization angle θ. As long as the q-axis component of the grid voltage obtained by the current synchronization angle θ through coordinate transformation is not equal to zero in the rotating coordinate system, it indicates that the current synchronization angle is not completely synchronized with the grid voltage, resulting in a corresponding change in the angular frequency correction Δω of the PI output , and the output synchronous angle θ also changes, and the θ angle obtained when the closed-loop is stable is the required grid voltage synchronous angle. Compared with the traditional hardware phase-locked loop that relies on zero-crossing detection, the software phase-locked loop can simplify the hardware circuit, and at the same time, it can enhance the ability to suppress harmonic interference and voltage distortion with the help of flexible software filtering measures.

Claims (5)

1. A traction power supply device based on a PWM rectifier, the device includes: a transformer, a rectifier, a control board, a host computer and a switching power supply, the switching power supply provides power for the control board; the primary side of the transformer is connected to the AC grid, and the secondary side is connected to the rectifier The input end of the rectifier is connected to the DC catenary; it is characterized in that the rectifier adopts a PWM rectifier, and the PWM rectifier is connected to the optical fiber interface circuit on the control board. Control, send out 6 PWM pulses, drive the power switch tube in the PWM rectifier to work; The control board includes: a conditioning circuit, a fault detection circuit, DSP, CPLD, memory, an optical fiber interface circuit and an Ethernet interface circuit; the specific connection relationship is: the input of the conditioning circuit is connected to the sensor in the main circuit, and the output of the conditioning circuit is connected to the DSP Sampling, connected to the fault detection circuit at the same time, the output of the fault detection circuit is connected to the CPLD; the PWM port of the DSP is connected to the CPLD, and then connected to the optical fiber interface circuit through the CPLD; in addition, the DSP is connected to the memory through the I2C bus; the data line and address line of the DSP The read and write signal lines are connected to the Ethernet interface circuit. 2. A kind of traction power supply device based on PWM rectifier according to claim 1, is characterized in that, the connection between the devices that constitute PWM rectifier: Connect the A-phase voltage sensor (1) and B-phase voltage sensor (2) to the A and B phases of the secondary side of the transformer respectively; The other end of the filter inductor (4) is respectively connected to the midpoint of the three intelligent power modules (5, 6, 7), and the tops of the three intelligent power modules are connected together to one end of the fuse (8), and the other end of the fuse Connect to the positive terminal (P) of the filter capacitor (10) on the DC side, and install the DC current sensor (9) on the positive terminal (P). The bottom terminals of the three intelligent power modules are also connected together to the negative terminal of the DC support capacitor (C). terminal N; a DC voltage sensor (11) is connected between the positive terminal (P) and the negative terminal N; The AC inductance (4), the AC filter capacitor (3) and the leakage inductance of the grid side transformer form an asymmetrical T-shaped filter. 3. A traction power supply device based on a PWM rectifier according to claim 2, characterized in that the AC filter capacitor (3) is a non-polar capacitor connected in a star shape. 4 . The traction power supply device based on PWM rectifier according to claim 1 , wherein the transformer is an epoxy resin casting dry-type transformer, and both the primary side and the secondary side are star-connected. 5. A traction power supply device based on PWM rectifier according to claim 1, characterized in that the upper computer and the control board are bidirectionally connected via Ethernet.

Images