KR20050060551A - Prt vehicle speed control and a method of supplying electric power to vehicle utilizing linear induction motor - Google Patents

Abstract

The present invention attaches a primary core of a linear induction motor to a guideway in a method of driving a personal rapid transit (PRT), which is a means of transporting cargo and passengers. In the method of mounting and driving a core in a vehicle, the current conductor of the secondary core is wound without using a plate or ladder structure made of aluminum or copper, and is wound using a coil, and a power circuit represented by a resistor or an inverter is wound around the winding terminal. The present invention relates to a concept, a structure, and a control method of connecting a thrust of a vehicle and simultaneously supplying electric power necessary to the interior of the vehicle by using electromotive force induced in the secondary core. Using the proposed method, we can control the thrust and speed of the vehicle, and use the electromotive force induced in the secondary core of the linear induction motor, which is necessary for the interior lighting, cooling / heating, ventilation, communication device and control system of the vehicle. The ability to supply DC power eliminates the need for additional power supplies such as pantographs or inductive power transfer units. Therefore, there is a feature that a simple and significant cost reduction effect is expected in terms of circuits and facilities as compared to the conventional method.

Description

PRT Vehicle Speed Control and a Method of Supplying Electric Power to Vehicle Utilizing Linear Induction Motor

The present invention relates to a driving and power supply method of a PALTI vehicle to which a linear electric motor is applied. A typical method of the related art mounts a primary core of a linear induction motor in a vehicle as illustrated in FIG. 1, and connects an inverter to a winding of the primary core to apply an alternating current. On the other hand, a guide plate is installed with a reaction plate composed of an aluminum plate and an iron plate or a copper plate and an iron plate, and exciting the primary core thereon causes an induction current to flow in the aluminum or copper plate. Thrust is obtained by the interaction of the magnetic force lines, and the vehicle moves. Current supplied to the inverter is supplied through a pantograph, inductive power transfer equipment, or a battery.

Power for driving Palti or power for cooling / heating, lighting, system control, etc., must be supplied to a moving vehicle, which is a pantograph or a non-contact inductive power transmission device as shown in FIG. power transfer equipment). However, since Palti vehicles pass through many switching sections, the use of pantograbs complicates the design of the guideway structure and is difficult to repair, and the contactless induction power transfer device eliminates contact problems. The disadvantage is that the price goes up. In the present invention, the winding of the secondary core of the linear induction motor is a winding type, by connecting the power conversion device to control the thrust of the vehicle and at the same time to supply the necessary electricity inside the vehicle separate panto grab or induction power transmission device It is a technical problem that the present invention intends to achieve without using.

The PALTI driving system proposed by the present invention is shown in FIG. 3. 4 and 5 are conceptual diagrams of the proposed system structures. In the proposed system structure, as shown in FIG. 3, the primary core of the linear motor is laid continuously or at a constant cycle in the guide way, and electricity of a system having a constant voltage and a constant frequency is directly input to the winding of the primary core. At this time, the primary core flows at a fixed frequency of 50 or 60 hertz, and a traveling magnetic wave is generated at the core pole face at that speed. The secondary core is mounted on the vehicle and the winding structure of the core is made of winding type.

When the resistance is connected to the end of the secondary winding as shown in FIG. 5 and the resistance value is adjusted, the generated thrust is changed to control the speed of the vehicle. Specifically, when the resistance value is increased, the low speed torque is large, which is advantageous for starting, and when the resistance value is decreased, it is advantageous for high efficiency operation at high speed. This is like driving a crane with secondary resistance control of a wound induction motor.

6 is a single-phase equivalent circuit of the linear induction motor, and has an equivalent circuit having the same structure as that of the wound induction motor. , The secondary input power Mechanical power When ignoring the copper loss and iron loss of the motor, the following relation holds.

here Is the speed of the secondary core, Thrust, Is the electrical angle speed of primary voltage, Is the slip speed. In the proposed system architecture Is fixed at 50 or 60 hertz (Hz), so that the frequency generated by the inverter is a slip frequency at steady state. Should be operated. Inverters are usually operated in a mode that absorbs power. Moreover, adjusting the ratio of current and voltage at the inverter terminal is equivalent to changing the resistance equivalently. Increasing the voltage and current ratio of the inverter terminal at the same load is equivalent to increasing the secondary resistance, and the speed is reduced. A graph in which the speed changes when the secondary resistance value is changed to a load having a constant value with respect to frequency is illustrated in FIG. 7. In addition, the power applied by the primary side when the vehicle speed is low and high speed, the power consumed by the linear motor, and the power absorbed by the inverter are illustrated in FIG. 8.

In the present invention, the equivalent resistance value represented by the inverter is converted, but a small resistance value for a large speed, a large resistance value for a small speed. 9 illustrates an inverter control method of the present invention, in which a speed controller configured as a proportional integral controller sets an inverter output voltage V in inverse proportion to the output A of the speed controller and in proportion to the current I flowing in the secondary winding of the motor. In FIG. 9, the secondary winding of the motor is represented by a transfer function 1 / (Ls + R). Where L and R are the inductance and resistance of the secondary winding, and s is the Laplace operator.

In addition, when the secondary winding is connected to the arm of the inverter as shown in FIG. 10, and the inverter generates a voltage corresponding to the sleep frequency, the power is transferred to the DC link, and this power is supplied to the DC-to-DC converter. It is used to charge the battery. The electric power passed to the DC link is expressed as the product of the motor thrust generation and the slip speed when ignoring the copper loss.In the case where the thrust is continuously generated at a high speed, too much energy flows into the DC link and the voltage across the DC link capacitor increases. Can be. If the DC link capacitor voltage rises more than necessary, the capacitor and the semiconductor switching element are burned out. In order to prevent such an overvoltage, as shown in FIG. 12, an overvoltage prevention circuit (dynamic braking circuit) can be connected to the DC capacitor in parallel to prevent overcharging by burning the power introduced more than necessary. On the contrary, if the vehicle consumes a lot of energy, such as using an air conditioner, and it is difficult to maintain the voltage of the battery due to the power flowing into the inverter, the linear motor may be mechanically fixed at the station. It can drive a large amount of energy through the inverter and charge the battery through a DC-to-DC converter. In addition, if more energy is required immediately while driving, generating more thrust also increases the power flowing into the inverter, and the increase in speed beyond the required thrust can be limited by using a mechanical brake.

FIG. 13 shows an example of using a low-cost power conversion circuit using three power switching elements and three diodes instead of an inverter. This circuit requires only half the switching element compared to the inverter, and thus the number of gating circuits of the switching element can be half the price of the hardware can be significantly lowered. 13 is a variation of the inverter, wherein the upper end of the switching arm is simply composed of a diode. The driving principle is as follows. When all three lower switches are turned on, the secondary windings of the linear induction motors are shorted and become in the same state as a squirrel cage induction motor, so that a large amount of current flows, and all three lower switches are turned on. When turned off, a circuit, such as a three-phase diode rectifier, is configured so that the voltage induced in the secondary winding of the linear induction motor flows through the DC link capacitor, causing charge. At this time, the thrust is lowered. You can control the thrust and energy going to the DC link by turning on or off three switches at the same time. Specifically, when the turn-on duty of the three switches is increased, the thrust is generated a lot, and when the turn-off duty is increased, the thrust is reduced and the energy flowing to the DC link is increased. This is called thrust pulse width modulation. Figure 15 shows the current flowing through the diode and the DC link when the three switches off. FIG. 16 illustrates that when three switches are turned on, current flows through a switch or a lower diode according to the current direction, and does not flow through a DC link.

FIG. 14 is a structure in which the negative terminal of the DC link of the power conversion circuit illustrated in FIG. 13 is connected to the neutral point of the secondary winding. In the circuit structure of FIG. 13, three switches must be turned on and off at the same time, whereas the circuit structure of FIG. 14 can turn on and off one, two, or three switches as needed to allow more precise thrust control and power inflow. That is, when only one switch is turned on for acceleration, the thrust increase is relatively small, when two switches are turned on, it is larger, and when three switches are turned on, the maximum thrust is generated. In addition, the greatest amount of energy is delivered to the DC link when all the switches are turned off, and the least amount of energy is drawn when only one switch is turned off. FIG. 17 shows that when one switch is turned on, a single-phase circuit is established and current flows through the one-phase and neutral points of the secondary side, and FIG. 18 shows two-phase when two switches are turned on. The circuit is established to show that current flows through the winding of the neutral and secondary two phases.

FIG. 19 illustrates the layout of the PALTI guideway, showing that the primary cores of the linear induction motors indicated by the squares are enumerated in the guideway and the driving guideway into the station. In addition, the primary winding of the linear induction motor is directly magnetized to the power supply having a certain frequency of the system, and the thrust control of the vehicle is achieved through the power conversion circuit installed in the vehicle, thereby installing the inverter for each guideway linear induction motor. This requires significantly fewer inverters than conventional methods.

The present invention proposes a method for supplying power required inside a vehicle without a panto grab or expensive inductive power transmission device, which is difficult to install and manage as a power receiver circuit of a PTI system vehicle. Therefore, the guideway is simplified, the construction cost is lowered, and the maintenance cost is reduced, thereby reducing the operating cost.

1 is a conceptual diagram of supplying power using a penta grab to a conventional Palti vehicle

2 is a conventional inductive power transfer (Inductive power transfer) structure

3 is a schematic diagram of the arrangement and system of a linear induction motor for driving a Palti vehicle and supplying power to the vehicle.

4 is a conceptual diagram of charging a vehicle internal battery by connecting a power converter and a DC-to-DC converter to a secondary core of a proposed PALTI linear induction motor;

5 is a conceptual diagram of controlling the speed of the vehicle by changing the secondary resistance value of the linear induction motor

6 is a single-phase equivalent circuit when an inverter is connected to a secondary winding of a linear induction motor and operates equivalently with a resistance.

7 is a relation between thrust and frequency according to load line and secondary resistance change

8 is an example of the ratio of power when the vehicle speed is low and high speed

9 is a block diagram showing a proposed method of controlling the speed by operating an inverter connected to a secondary winding of a linear induction motor with an equivalent variable resistance.

10 is a diagram of signal levels for speed control by connecting an inverter to a linear induction motor secondary winding;

11 is a circuit diagram in which an inverter is connected to a secondary winding of a linear induction motor.

12 is a circuit diagram in which an inverter with an overcharge protection circuit is connected to a secondary winding of a linear induction motor.

13 is a circuit diagram of a power converter in which an upper semiconductor switch of an inverter arm is replaced with only a diode;

FIG. 14 is a circuit diagram of connecting the neutral point of the secondary winding of the linear motor, which is wired (Y), to the (-) end of the power converter replaced by a diode.

FIG. 15 is a flow chart of a case where all of the lower switches are turned off or only a diode rectifier is included in the power conversion circuit of FIG. 14.

FIG. 16 is a current flow chart of the power conversion circuit of FIG. 15.

FIG. 17 is a current flow chart when only one of three switches is turned on in the power conversion circuit of FIG.

FIG. 18 is a current flow chart when only two of three switches are turned on in the power conversion circuit of FIG.

19 is a proposed structure for powering the primary winding of a linear induction motor arranged on a Palthy guideway.

<Description of Symbols for Major Parts of Drawings>

1: Commercial power supply (60Hz, three phase AC)

2: electric vehicle

3: induction motor secondary core and winding corresponding to induction motor rotor

4: electric motor drive

5: power circuit (AC / DC converter or DC / DC converter)

6: additional power supply line

7: Pantograph

8: Magnet corresponding to stator magnet of synchronous motor

9: Primary core and winding corresponding to stator of induction motor

10: power conversion circuit

11: resistance of primary winding

12: primary leakage inductance

13: secondary leakage inductance

14: resistance of secondary winding

15: Primary and secondary mutual inductance

16: motor drive circuit

17: primary inductance

18: secondary inductance

19: DC / DC power converter

20: battery (storage battery)

21: semiconductor power switch element

22: diode

23: DC capacitor

24: neutral point

25: overvoltage protection system

26: variable resistance

28: resistance

Claims (5)

In a physical rapid transit system in which a primary core of a linear induction motor is continuously or periodically attached to a guideway and a linear motor secondary core is mounted on a vehicle to obtain propulsion. Connect the wound primary winding directly to AC power or power system with fixed frequency, and select linear motor secondary core as slotted winding type, connect variable resistance to secondary winding or power conversion using semiconductor represented by inverter How to control the thrust of the vehicle by connecting circuits. The method according to claim 1, wherein when the three-phase voltage source inverter is connected to the secondary winding of the linear induction motor, the output voltage of the inverter inverter is set to be proportional to the current flowing in the secondary winding, thereby operating equivalently with the resistance. How to control the speed of the linear induction motor by setting the value to the output of the speed controller. The method according to claim 1, wherein when the three-phase voltage source inverter is connected to the secondary winding of the linear induction motor, the power supplied to the DC link when the inverter is operated is used as a power source required directly inside the vehicle, or a DC-to-DC converter How to charge the battery via Instead of a three-phase inverter, the upper three elements of the three-phase inverter arm connect a simplified power conversion circuit with a diode only to the secondary winding of the linear induction motor and turn on the lower three switching elements simultaneously. Gain on thrust and turn on and off to adjust the on-duty and off-duty to energize the DC link to achieve the desired thrust and the amount of energy needed inside the vehicle. How to accept it.  By connecting the negative terminal of the DC link of the simplified power conversion circuit of claim 4 to the neutral point of the Y-wired secondary winding, the lower switches can be operated separately to obtain thrust and to transfer energy toward the DC link. How you can.