WO2016101380A1 - Semi-vehicle-mounted rapid charging method and charging device thereof for electric bus - Google Patents

Abstract

Provided are a semi-vehicle-mounted rapid charging method and a charging device thereof for an electric bus; said electric bus comprises a motor controller and a high-voltage battery; the three-phase AC power outputted by a three-phase AC power grid is isolated and stepped-down, then filtered; the motor controller performs AC-DC conversion on the filtered three-phase AC power, converting same to DC power; the DC power is filtered, then rapidly charges the high-voltage battery. The semi-vehicle-mounted charging method and charging device thereof for an electric bus provide the same simple, convenient, and flexible charging modes of a vehicle-mounted charger, while also overcoming the limitations of volume and cost, and provide a charging current having the same power level as a non-vehicle-mounted charger and increase charging flexibility for electric buses.

Description

Electric bus half-car fast charging method and charging device thereof Technical field:

The invention relates to a semi-vehicle fast charging method for an electric bus and a charging device thereof, and belongs to the technical field of electric vehicle charging.

Background technique:

Contact chargers are mainly divided into two types: on-board chargers and off-board chargers. The car charger is a charger that is fixedly mounted on the electric car. The charging method is simple, the flexibility is good, and the charging station with the matching is less, but the charging speed is slow and the time is long. The reason is that the space available on the electric vehicle is small, and in order to reduce the self-weight of the electric vehicle, it is necessary to ensure that the on-board charger is small in size and light in weight when manufacturing the on-board charger. Due to the volume cost problem, a high-power car charger with a current of several hundred amperes cannot be applied to an electric bus.

The off-board charger requires a charging pile, which is installed in a fixed position compared to the on-board charger, and is a device for charging a high-voltage battery of an electric vehicle. Compared with on-board chargers, off-board chargers are not limited by size and can provide up to hundreds of kilowatts of power handling capability to quickly charge electric buses. However, the charging method of the non-vehicle charger is complicated, and the charging station with the matching is large, and the flexibility is relatively poor.

For high-power electric buses, a high-power level controller is required to drive the motor or to quickly charge the high-voltage battery. The controller includes IGBT power module, sampling, driving, protection, heat dissipation, control and other functional circuits. The traditional charge controller is completely independent of the motor controller and is expensive. If the motor controller can be used to complete the charging process, the cost of the electric bus charging system can be reduced and space can be saved. In addition, if the large-volume portion of the charging device can be placed on the ground, it is possible to overcome the space limitation of the high-power car charger and maintain the flexibility of the in-vehicle charger.

Summary of the invention:

The object of the present invention is to provide a semi-vehicle fast charging method for an electric bus and a charging device thereof, which can inherit the simple, convenient and flexible charging mode of the vehicle charging device, and can overcome the volume cost limitation and provide off-board charging. The same power level of the charging current, increase the electric bus The charging flexibility of the car expands the adaptability and activity space of the electric bus, and the overall performance is superior, which promotes the development of the electric bus industry.

The object of the present invention is achieved by the following technical solutions.

The utility model relates to a semi-vehicle fast charging method for an electric bus, wherein the electric bus comprises a motor controller and a high-voltage battery, and the three-phase alternating current outputted by the three-phase alternating current grid is filtered after being stepped down, and the motor controller filters the three-phase after filtering. The alternating current is converted into direct current by AC-DC conversion, and the direct current is filtered to quickly charge the high voltage battery.

The above-mentioned isolation buck is to reduce the three-phase AC output from the 380V three-phase AC grid to a three-phase AC of 280V or less through a step-down transformer.

The motor controller described above comprises a microprocessor unit, a driving circuit unit and an IGBT module. The microprocessor unit outputs a PWM signal to the driving circuit unit, and the driving circuit unit controls the IGBT module to perform AC-charging of the three-phase alternating current after filtering. DC conversion.

The high voltage battery described above can be charged in a fast charging mode of 1 C or higher.

The utility model relates to an electric bus semi-vehicle quick charging device, which comprises a ground part and a vehicle part arranged on the electric bus, the ground part comprises a step-down transformer and an AC filter circuit, and the vehicle part comprises a motor controller, a DC filter circuit and a high voltage battery, and a three-phase The three-phase AC output of the AC power grid is isolated and stepped down by the step-down transformer, and then filtered by the AC filter circuit. The motor controller converts the three-phase AC power after the conversion into AC power by DC-DC conversion, and the DC power is filtered by the DC filter circuit. High-voltage battery for fast charging.

The AC filter circuit described above employs a three-phase LC or LCL type filter.

The DC filter circuit described above employs a single-phase CLC type filter.

The above-mentioned ground part is provided with a charging pile interface one, and the charging part interface 2 is arranged in the vehicle-mounted part. In the charging state, the charging pile interface 1 and the charging pile interface 2 are connected together by a charging gun.

The charging gun described above is provided with a three-phase power line, a neutral line, a ground line, a control guide line, and a CAN communication line.

One of the above-mentioned ground portions can be connected to a plurality of vehicle-mounted portions at the same time.

A fuse is disposed between the three-phase AC power grid and the step-down transformer described above.

The charging pile interface 2 described above is connected to the motor controller through the contactor 2. The three-phase coil winding of the electric bus driving motor is connected between the contactor 2 and the motor controller through the contactor.

The contactor 3 is connected in parallel at both ends of the contactor 2, and the contactor 3 is connected in series with the pre-charging resistor.

The contactor 4 is connected in parallel at both ends of the DC filter circuit, and the output end of the DC filter circuit is connected to the high voltage battery through the contactor 5.

The charging pile interface 1 and the charging pile interface 2 described above are connected in parallel by two or more charging guns.

Compared with the prior art, the invention has the following effects:

1) The ground part includes the step-down transformer and the AC filter circuit. The electric bus fast charging device needs hundreds of kW of charging power and several hundred amps of charging current, which causes the high-frequency step-down transformer and the filter inductor and filter capacitor to be large and heavy. The electric bus is limited by space and weight, and cannot withstand such high-power step-down transformers and filter inductors and filter capacitors. Therefore, it is placed on the ground part, saving space and reducing costs;

2) The ground-phase step-down transformer is used to reduce the grid 380V voltage level to a three-phase AC voltage level of 280V or less. The AC-DC converter of the motor controller is actually a BOOST boost circuit, 380VAC three-phase input, the minimum voltage that can be output after being converted into DC by the motor controller is 540VDC. At present, the rated maximum voltage of the universal high-voltage battery is about 460V. If the three-phase alternating current output from the three-phase AC power grid is not stepped down, when the high-voltage battery voltage is at the rated minimum allowable voltage, the three-phase alternating current is converted into a direct current by the motor controller. The lowest voltage that can be output will be higher than the lowest voltage allowed by the high voltage battery, resulting in the charging device not being able to charge the high voltage battery. After the three-phase AC output of the three-phase AC power grid is stepped down by the step-down transformer, the minimum DC voltage that can be output after the three-phase AC power is AC-DC converted by the motor controller is not higher than the minimum voltage allowed by the high-voltage battery. , thereby ensuring that the charging device can charge the high voltage battery within the allowable full voltage range;

3) The AC filter circuit of the ground part is a three-phase filter whose topology is LC or LCL type filter. The LCL filter has better high-frequency ripple filtering performance than the single-inductor L-type filter at the same inductance, which can reduce the cost and volume while ensuring the filtering performance. Since the three-phase transformer itself has a leakage inductance, it is equivalent to a small value inductor, which can replace the grid side inductance of the LCL filter. Therefore, in order to simplify the topology, an LC type filter is generally used. The LC or LCL type filter has a three-phase shunt capacitor bank. When the charging device starts, stops or the grid fails, the charging circuit has a sudden change in current, and the capacitor bank can buffer the abrupt current to ensure the safety performance of the device. The AC filter circuit designed by the invention has better high-frequency ripple filtering performance and safety reliability than the single-inductance L filter circuit, and can reduce volume and save cost;

4) The DC filter circuit is a single-phase filter whose topology is a CLC type filter. The capacitor on the motor controller side is mainly used to filter out the high frequency ripple generated by the switch tube of the motor controller; the capacitor on the high voltage battery side is mainly used to filter out low frequency ripple and energy storage; the inductor is mainly used for flat wave and reduce charging current. Ripple. The national standard has strict regulations on the output ripple current of the charging device, and needs to be guaranteed within 1%. The DC filter circuit designed by the present invention is designed to meet the standard, so that the high-voltage battery has reduced heat generation, extended life, and overall performance. Superiority to promote the development of the electric bus industry. When the motor controller performs PWM rectification to convert AC power into DC power, the DC side outputs a high-frequency pulse current equal to the switching frequency of the IGBT module. If only a simple capacitor C is used for filtering, the charging current output by the charging device will contain a large amount of Ripple current makes the high-voltage battery have serious heat generation, shortened life, and even burned overheated;

5) In the charging state, the charging pile interface 1 and the charging pile interface 2 are connected in parallel by two or more charging guns to reduce the current of the single charging gun, and at the same time increase the charging flexibility of the electric bus, and expand the electric motor. The adaptability and activity space of the bus;

6) Using the electric bus motor controller for fast charging, the charging power is large, and the charging current can reach the current level of the driving motor, up to thousands amps. The motor controller integrates the motor driving and charging functions, and the motor controller is used as a charging controller, and basically does not need to add extra cost or volume;

7) The motor controller converts the three-phase alternating current after filtering into AC power by AC-DC conversion. Not only can the high-voltage battery be quickly charged, but also the power factor correction and harmonic compensation can be performed on the input side of the grid, so that the fast charging device will not interfere with the power grid and ensure the power quality of the grid.

BRIEF DESCRIPTION OF THE DRAWINGS:

1 is a block diagram showing the structure and principle of an electric bus semi-vehicle quick charging device in an embodiment;

Figure 2 is a detailed topological view of the ground portion of the fast charging device;

Figure 3 is a detailed topological view of the onboard part of the fast charging device;

4 is a schematic diagram of three-phase voltage and current on the AC side of the fast charging device during startup, charging, and stopping;

FIG. 5 is a schematic diagram of DC side output current, capacitor voltage, and battery voltage of the fast charging device.

detailed description:

The present invention will be further described in detail below by way of specific embodiments and with reference to the accompanying drawings.

As shown in FIG. 1 , the embodiment is a semi-vehicle fast charging device for an electric bus, comprising a ground part and a vehicle part disposed on the electric bus, the ground part comprises a step-down transformer and an AC filter circuit, and the vehicle part comprises a motor controller. The DC filter circuit and the high-voltage battery, the three-phase AC output of the three-phase AC power grid is isolated and stepped down by the step-down transformer, and then filtered by the AC filter circuit, and the motor controller converts the three-phase AC power after the conversion into AC-DC conversion into DC power, DC power is quickly charged by the DC filter circuit to quickly charge the high voltage battery.

In the charging state, the three-phase AC output of the 380V three-phase AC power grid is isolated and stepped down to three-phase AC power of 280V or less by the step-down transformer, and then filtered by the AC filter circuit, and the motor controller is used as the controller of the charging device. The processor unit outputs a PWM signal to the driving circuit unit, and the driving circuit unit controls the IGBT module to perform AC-DC conversion on the filtered three-phase alternating current, convert the filtered three-phase alternating current into direct current, and the direct current is filtered by the direct current filtering circuit. Fast charging of high voltage batteries;

In the motor driving state, the detecting circuit detects the motor operating parameter and sends it to the microprocessor unit. The microprocessor unit outputs a control signal to the driving circuit unit, and the driving circuit unit controls the IGBT module to convert the DC power stored on the high voltage battery into three. Phase AC output to provide power to the drive motor The motor rotates.

As shown in Fig. 2, in the actual fast charging device, the output end of the three-phase AC power grid needs to be connected to the step-down transformer T through the fuse QF1, and the fast charging device passes the fuse QF1 during the overcurrent or overhaul process. The AC grid is disconnected from the fast charging device. The transformer must use a step-down transformer to ensure that the minimum voltage of the three-phase AC must be lower than the initial voltage of the rechargeable battery after the AC filter current is rectified under the maximum allowable voltage input condition, otherwise the battery cannot be charged. In this embodiment, the AC filter circuit uses an LC filter, including an inductor L1 and capacitors C21, C22, and C23, to filter the high-frequency ripple generated by the IGBT module to ensure power quality of the grid.

A charging pile interface 1 is arranged on the ground part, and a charging pile interface 2 is arranged in the vehicle part. In the charging state, the charging pile interface 1 and the charging pile interface 2 are connected in parallel by two or more charging guns. In this embodiment, the charging pile interface 1 and the charging pile interface 2 are connected together by two parallel charging guns. The charging gun is provided with a three-phase power line, a neutral line, a ground line, a control guide line, a CAN communication line, and the like. The charging pile interface can be connected to multiple charging pile interfaces 2 at the same time.

As shown in Figure 3, the charging pile interface 2 is connected to the motor controller through the contactor KM2, and the contactor KM2 is used to isolate the three-phase AC network, the drive motor and the motor controller. The three-phase coil winding of the electric bus drive motor is connected between the contactor KM2 and the motor controller through a contactor KM1 to ensure that the drive motor is isolated from the three-phase AC grid during charging. A contactor three KM3 is connected in parallel at both ends of the contactor KM2, the contactor three KM3 is connected in series with the pre-charging resistor, and the contactor three KM3 is used to turn on the pre-charging resistors R1, R2 and R3, when the DC side capacitor voltage is over When low, pre-charge it to prevent excessive current flow. The contactor four KM4 is connected in parallel at both ends of the DC filter circuit, and the contactor four KM4 is used to bypass the DC filter circuit. In the charging state, the contactor KM4 is in the off state, and the contactor four KM4 is in the closed state in the motor driving state. The output of the DC filter circuit is connected to the high-voltage battery through the contactor KM5. In the emergency state, the motor controller, DC filter circuit and high-voltage battery are completely isolated by the contactor KM55 to ensure the safety of the system.

The current sensors CT1, CT2, CT3 are used to detect the AC side three-phase input and output current, and the current sensor CT4 is used to detect the DC side input and output currents, and the current signals detected by the current sensor are all Will be input to the microprocessor for processing. The DC side voltage detection and the grid three-phase voltage detection are not shown here, but it is known that the DC side voltage detection and the grid three-phase voltage detection are detected by a non-isolated differential circuit.

In the DC filter circuit, C1 and C2 are thin film capacitors for filtering high frequency ripple; C3 and C4 are electrolytic capacitors for flat wave energy storage; L _DC is DC side filter inductor; R5-R8 is voltage equalization resistance.

In the charging state, the contactor KM1, the contactor three KM3, the contactor four KM4 are disconnected, the contactor two KM2, the contactor five KM5 is closed, and the ground part of the three-phase AC power grid output 380VAC three-phase alternating current is stepped down and filtered. After that, the vehicle is connected to the vehicle through the charging gun, converted into direct current by the IGBT module, and the direct current is filtered by the DC filter circuit to quickly charge the high voltage battery;

In the motor driving state, the contactor KM2, the contactor three KM3 are disconnected, the contactor KM1, the contactor four KM4, the contactor five KM5 are closed, the DC filter circuit is bypassed, and the high voltage battery stores the DC current through the contactor five. KM5 and contactor four KM4 are converted into three-phase alternating current by IGBT module. The three-phase alternating current is supplied to the motor through the contactor KM1, and the motor is driven to run.

The processes of starting, stopping, and troubleshooting of the quick charging device are not described in detail, and the state of the main circuit is converted by controlling the on and off of the contactor.

It can be seen from Fig. 4 that the motor controller PWM rectification control is adopted. When the motor controller is working, the sinusoidal input current of the AC side is better, the phase and the three-phase voltage are basically the same, the current ripple is relatively small, and the harmonic content is relatively low. The power factor is relatively high.

It can be seen from Fig. 5 that after the DC filter circuit adopts CLC filtering, the charging current fluctuates somewhat, but the whole is relatively smooth, and no high frequency ripple appears. When the capacitor voltage in the DC filter circuit is charged, there is a fluctuation of about 3V with the fluctuation of the current, and the whole is stable, and the effect is ideal.

Claims (15)

1. The utility model relates to an electric bus semi-vehicle fast charging method, wherein the electric bus comprises a motor controller and a high voltage battery, wherein the three-phase alternating current output of the three-phase alternating current grid is filtered after being stepped down, and the motor controller filters the The subsequent three-phase alternating current is converted into direct current by AC-DC conversion, and the direct current is filtered to quickly charge the high-voltage battery.
2. The method of claim 1 , wherein the isolating buck is to step down a three-phase alternating current output of a 380V three-phase AC power grid to a voltage of 280V or less through a step-down transformer. Three-phase alternating current.
3. The semi-vehicle fast charging method for an electric bus according to claim 1 or 2, wherein the motor controller comprises a microprocessor unit, a driving circuit unit and an IGBT module, and the microprocessor unit outputs a PWM signal to The driving circuit unit controls the IGBT module to perform AC-DC conversion on the three-phase alternating current after filtering.
4. The semi-vehicle fast charging method for an electric bus according to claim 1 or 2, wherein the high voltage battery is capable of charging the battery in a fast charging mode of 1 C or higher.
5. An electric bus semi-vehicle quick charging device comprises a ground part and an onboard part disposed on the electric bus, wherein the ground part comprises a step-down transformer and an AC filter circuit, and the vehicle part comprises a motor controller and a DC filter The circuit and the high-voltage battery, the three-phase AC output of the three-phase AC power grid is isolated and stepped down by the step-down transformer, and then filtered by the AC filter circuit, and the motor controller performs AC-DC conversion on the filtered three-phase AC power to convert into DC power, DC power The high voltage battery is quickly charged after being filtered by the DC filter circuit.
6. The electric bus half-vehicle rapid charging device according to claim 5, wherein the AC filter circuit uses a three-phase LC or LCL type filter.
7. The electric bus half-vehicle rapid charging device according to claim 5, wherein the DC filter circuit adopts a single-phase CLC type filter.
8. The electric bus half-vehicle quick charging device according to claim 5 or 6 or 7, wherein a charging pile interface 1 is disposed on the ground portion, and a charging pile interface 2 is disposed in the vehicle-mounted portion. In the charging state, the charging pile interface 1 and the charging pile interface 2 are connected together by a charging gun.
9. The electric bus half-vehicle quick charging device according to claim 8, wherein the charging gun is provided with a three-phase power line, a neutral line, a ground line, a control guide line and a CAN communication line.
10. A semi-vehicle fast charging device for an electric bus according to claim 5 or 6 or 7, wherein a ground portion can be simultaneously connected to a plurality of vehicle-mounted portions.
11. The electric bus half-vehicle rapid charging device according to claim 5, characterized in that a fuse is arranged between the three-phase AC power grid and the step-down transformer.
12. The electric bus half-vehicle quick charging device according to claim 8, wherein the charging pile interface 2 and the motor controller are connected together by the contactor 2, and the three-phase coil winding of the electric bus driving motor is contacted. The device is connected between the contactor 2 and the motor controller.
13. The electric bus half-vehicle rapid charging device according to claim 12, wherein a contactor 3 is connected in parallel at two ends of the contactor, and the contactor 3 is connected in series with the pre-charging resistor.
14. The semi-vehicle fast charging device for an electric bus according to claim 5 or 6 or 7, wherein a contactor 4 is connected in parallel at both ends of the DC filter circuit, and an output end of the DC filter circuit passes through the contactor 5 and the high voltage battery. connected.
15. The electric bus half-vehicle quick charging device according to claim 8, wherein the charging pile interface 1 and the charging pile interface 2 are connected in parallel by two or more charging guns.

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