JPH0734601B2 - Controller for linear motor type electric vehicle - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a frequency control system for a linear motor for electric vehicle propulsion, and in particular, it is equipped with a synchronous speed detection wheel diameter error correction device suitable for a linear induction motor type electric vehicle. And a frequency control method for a linear motor type electric vehicle.

[Background of the Invention]

In principle, the linear induction motor is a rotary induction motor linearly developed, and the control method may be exactly the same. Regarding the frequency control of an induction motor type electric vehicle, the inverter and other power converters are operated at a frequency that detects the number of rotations of the motor shaft and knows the synchronous frequency, and then adds the slip frequency to it (subtracts during regenerative braking). It is common to do. However, when the wheel spins, the motor shaft speed increases regardless of the vehicle body speed. Therefore, if frequency control is performed on the basis of this, there is a drawback that the frequency is further increased and a large slip occurs. As one method for solving this, JP-A-56-107707
As shown in the publication, there is a method of using the rotation speed of non-driving wheels as a frequency reference. In this case, it is necessary to correct the error due to the difference in diameter between the drive wheel and the speed detection wheel, and a specific method thereof is described in the above-mentioned publication.

By the way, in order to control the linear induction motor, frequency control may be performed based on the rotation speed of the wheels (all of which are non-driving wheels in this case). However, regarding the correction when the wheel diameter changes due to wear, the rotary motor Not as easy as.

[Object of the Invention]

An object of the present invention is to provide a frequency control method suitable for a linear induction motor type electric vehicle.

[Outline of Invention]

Therefore, in the present invention, a ground element for measuring the absolute vehicle speed is installed at a predetermined rail position. The synchronous frequency f ₀ (Hz) of the linear induction motor is expressed as f ₀ = v / 2τ (1) when the vehicle speed is v (m / s) and the ball pitch is τ (m), so the vehicle speed can be directly measured. Required. For this reason, the vehicle body speed is measured from the time it takes to pass between a plurality of ground elements installed at a predetermined interval.

Example of Invention

 An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, a linear induction motor 1 is mounted on a trolley 3 so as to maintain a predetermined gap with a reaction plate 2. The main purpose of the wheels 4 is to support the load of the vehicle body 5, and does not serve to transmit the driving force. A pulse encoder 6 as a speed detector is provided at the shaft end of the wheel 4 to generate a pulse having a frequency proportional to the speed.

Further, the ground elements 7, 7'are installed near the rail with a predetermined distance l. A car upper member 8 is provided on the vehicle body so as to face the ground member.

The linear induction motor 1 is energized by a power conversion device 9 such as an inverter or a cycloconverter attached to the vehicle body.

In such a configuration, the frequency control signal is processed by the frequency control device 10 of the block diagram as shown in FIG. The frequency of the pulse train obtained from the pulse encoder 6 represents the vehicle speed, that is, the moving speed of the linear motor. If the diameter of the wheel 4 is as designed, the moving speed is accurately represented. If the frequency corresponding to the moving speed is fp, then fp can be made equal to the synchronous frequency f ₀ at that speed. However, the wheels 4 wear, and when the brakes are applied too much and the wheels slide, a local flat surface is formed on the tread surface, so that the wheels are sometimes ground to reduce the diameter. Then, the pulse encoder output fp no longer corresponds exactly to the synchronization frequency f ₀ .

For this reason, it is necessary to correct the error due to the change in the wheel diameter by the frequency correction circuit 11 at all times during operation to restore the accurate synchronization frequency f ₀ . The correction coefficient k is stored in the memory circuit 12 and is rewritten from time to time.

When the synchronous frequency f ₀ is obtained, the slip frequency fs is added / subtracted to give the inverter frequency f, which is given to the gate controller 13. In addition to this, the gate control device 13 receives a current command, a voltage command, a notch command, etc., and controls the gate signal of the thyristor of the inverter.

These configurations are well known for controlling rotary induction motors, and it will be easily understood that linear motors also operate on the same principle.

Now, a method of rewriting the correction coefficient k stored in the memory circuit 12 will be described.

The train child 8 generates a pulse when passing over the ground child 7, and also generates a pulse when passing over the ground child 7 ′. From this pulse interval t (s), the vehicle speed v (m /
s) is as follows.

v = l / t (m / s) (2) where l (m) is the distance between the ground elements.

Substituting this into equation (1) gives the synchronization frequency f ₀ ,
A circuit for obtaining the synchronous frequency f ₀ from the pulse interval t as described above is called a synchronous frequency calculation circuit 14.

Comparing the output f ₀ of the synchronous frequency calculation circuit 14 with the output frequency fp of the pulse encoder 6, if the diameter of the wheel 4 is as designed, they should be the same. However, if there is an error in the wheel diameter, fp and f ₀ are slightly different, so the ratio k = f ₀ / fp (3) can be calculated. This k is referred to as a correction coefficient, and a portion for performing the calculation of the equation (3) is referred to as a correction coefficient calculation circuit 15.

Once the correction coefficient k is determined, the k is used for a while and the frequency correction unit 11 always calculates f ₀ = kfp ... (4) to convert the input fp to f ₀ .

Although one embodiment of the present description has been described in principle and the configuration of each unit has been described as a circuit, it is more convenient to perform processing by software using a microcomputer. A second embodiment will be described below with reference to FIG. FIG. 3 shows only a portion corresponding to the frequency control device 10 of FIG. 2, and portions having the same function are designated by the same reference numerals.

The pulse train obtained from the pulse encoder 6 is passed through the F / D converter 16 to be converted into a digital amount Fp proportional to the frequency fp of the pulse train, and given to the microcomputer 17.
Corrective calculation routine composed of software during normal driving
According to 11, the digital amount Fp is corrected using the correction coefficient K, and the digital amount Fp corresponds to the synchronization frequency correctly.
Converted to F ₀ . This gate controller 13 (not shown)
The digital amount corresponding to the slip frequency fs given by
Fs is added and subtracted, the operation result F is converted into a pulse train of frequency f corresponding to F by the DF conversion circuit 18, and the gate control device 13
Give to.

As described above, it is usually necessary to use the determined correction coefficient K, but since this has a different value when the diameter changes due to wheel wear, grinding, etc., the correction coefficient must be corrected from time to time. This calibration is performed as follows.

As described above, the pulse output from the car top 8 is t
(S). The digital amount V corresponding to the vehicle body speed v is obtained by the speed calculation routine 19 for calculating the speed between the pulses. From the speed v and the pole pitch τ, the synchronization frequency that should be at the current speed can be obtained using the relationship of the equation (1), and therefore F ₀ is calculated by the synchronization frequency calculation routine 20 that performs the calculation. The difference between this output F ₀ and the above-mentioned F p represents the error due to the fluctuation of the wheel diameter, and therefore the correction coefficient can be calculated. The simplest calculation formula is to calculate K as K = F ₀ / Fp (5) through the correction coefficient calculation routine 15 at the time of calibration and store it in the memory 12, and from the input Fp and the memory 12 during traveling. This is a method of correcting Fp by taking out K and setting F ₀ = KFp (6).

Actually, in order to correct with high accuracy, not a mere division / multiplication, but a method of extracting a difference and performing division on it is used, but in principle, the formulas (5) and (6) are sufficient, so it is omitted. To do.

The problem is when to perform this calibration. Since the memory 16 is rewritten, the output frequency f suddenly changes.
Inverter is stopped It is good during coasting. Further, since the pulse generated by the upper body 8 is relatively large, the change in the vehicle body speed must not occur during that period. Therefore, it is desirable to use a flat line that coasts at a constant speed. If the ground element is installed in such a place, a calibration command for determining that the condition is satisfied by capturing the coasting signal from the master controller (not shown) of the cab and the pulse signal that has passed through the ground element 7. A calibration signal is issued from the routine 21, and the correction coefficient is calculated and the memory 12 is rewritten.

A flow chart showing the operation of FIG. 3 is shown in FIG.
During the power running or the regenerative operation, the frequency correction mode is set, and the correction coefficient K in the memory is used to perform the correction calculation on Fp to calculate the synchronous frequency F ₀ . When passing over the ground element during coasting, the correction coefficient correction mode is set, the time t passing between the ground elements is read, the synchronization frequency F ₀ is calculated, and the correction coefficient K is calculated from this and Fp.
To calculate. In the case of manual correction, it is determined that there is a correction command and the correction coefficient is corrected. In the case of automatic correction, correction is performed because the calibration signal is established.

Since these operations are repeated in a short cycle (every few ms), the frequency can be corrected sufficiently corresponding to the ever-changing vehicle speed.

〔The invention's effect〕

As described above, according to the present invention, the speed detection error caused by the change of the wheel diameter can be corrected and the frequency control can be accurately adjusted to the vehicle body speed, so that the characteristics of the linear mom can be sufficiently drawn out and the smooth operation can be performed. Also, because you can automatically calibrate by simply coasting through a place with a ground element,
Maintenance work for adjustment is unnecessary.

[Brief description of drawings]

FIG. 1 is a system configuration diagram showing a carriage of a linear motor type electric train and sensors for speed detection relating to the method of the present invention, FIG.
FIG. 1 is a block diagram showing the flow of signals according to the method of the present invention,
FIG. 3 is a block diagram showing a signal flow when a microcomputer is used as the second embodiment of the present invention, and FIG.
The figure is a flow chart for explaining the operation of Fig. 3, 1 ... Linear induction motor, 6 ... Pulse encoder, 7,
7 '... ground element, 8 ... vehicle element, 14 ... synchronous frequency calculation section, 15 ... correction coefficient calculation section, 12 ... storage section, 11 ... frequency correction section.

Claims (1)

[Claims] 1. A linear motor for generating a propulsive force, a dolly equipped with the linear motor and traveling by wheels, a vehicle body supported by the dolly, an inverter for urging the linear motor, and a speed signal coupled to the wheels. In a controller for a linear motor electric vehicle equipped with a speed detector that generates a signal, and a gate controller that controls the gate signal of the inverter by inputting the output of the speed detector, a vehicle mounted on the vehicle body or the carriage. Child, a plurality of ground elements provided facing the car upper child at a predetermined interval in a section in which the electric vehicle coasts at a constant speed, the electric vehicle is coasting and has passed the ground element When calculating the vehicle speed from the output of the car
A correction coefficient calculation unit that calculates a frequency correction coefficient by comparing this output with the output of the speed detector, a storage unit that holds the frequency correction coefficient, and a correction coefficient that is stored in the storage unit. A linear motor type characterized in that a frequency correction unit for correcting the output frequency of the speed detector is provided, and a slip frequency given by the gate control device is added to or subtracted from the output of the frequency correction unit to obtain a frequency given to the gate control device. Electric vehicle control device.