JPS6289402A - Controlling method for electric railcar - Google Patents

Abstract

PURPOSE:To improve the efficiency of a regenerative braking by reducing the regenerative amount upon decreasing of a regenerative load and reducing a slip frequency in the state that the regenerative amount cannot be increased. CONSTITUTION:When a regenerative load decreases during the regenerative brake control of an induction motor 5 so that the voltage 8 of a filter capacitor 3 exceeds a throttle starting voltage 72 for decreasing a motor voltage VM, VM/fINV (fINV: inverter frequency) decreases. At this time when VM/fINV becomes a limiting value 73 or lower capable of suppressing the overvoltage at voltage overvariation time due to the application and the interruption of the load, it reduces the slip frequency fS. Thus, the regenerative brake does not fail by the protection of the overvoltage against the overvariation while the voltage 8 is clamped to an overvoltage protection set value 71.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a control method for an electric vehicle that stabilizes regenerative braking control of an electric vehicle driven by an induction motor.

[Conventional technology]

FIG. 2 is a circuit diagram of an electric vehicle in which an induction motor is controlled by a variable voltage variable frequency inverter (hereinafter referred to as an inverter). In the figure, (11 is a catenary (1 m) having a predetermined power and a current collector (1 m) that receives power from this catenary (1 m).
1b) is a power supply, (2) is a filter reactor, 1
3) is a filter capacitor, 14) is an inverter, (6)
) is an induction motor.

Such an electric car uses a filter circuit consisting of a filter reactor (2) and a filter capacitor (3) to
Power supply (11 to inverter (41 or inverter (4)
It absorbs disturbances from the power source (11).Generally, regenerative braking of electric vehicles is controlled based on the following equation.

'Engineering NV -'r -fs ・”I
ll However, fzNv: inverter frequency (rotating field frequency of induction motor), fr: rotor frequency.

fs: slip frequency, VM: motor voltage, IM:
Motor current, P: regenerative output, k: constant.

That is, braking is effected by making the frequency of the rotating magnetic field smaller than the rotor frequency (ur). At this time,
Ignoring the loss of the inverter (4), regenerative power (p) of the 1B1 type is obtained, and the power (p) can be fed back to the N source (1) as shown by the arrow in Figure @2.

However, if there is a load that consumes enough regenerative power (P), the power supply (11 side voltage and filter capacitor (3
) voltage increases (7f?) However, when the regenerated power (Pi is greater than the load power), the voltage of the power supply (1) and filter capacitor (31) will continue to rise.If the voltage continues to rise, Inverter (4) and power supply (
1) The devices connected to the device will be locked down due to overvoltage, and each device will stop.

For this reason, in general, in the -order voltage control of an induction motor (5), since the slip frequency (f8) is fixed, the motor voltage (vM) is decreased, and the regenerative power CP+ is decreased from the formula (2+, +31). Therefore, the motor voltage (VM) is controlled so that each device such as the inverter (4) operates at the maximum voltage at which it can operate.
In steady state, control is performed so that the voltage is clamped to the maximum voltage, and when a load is applied, the power supply voltage decreases, so the motor voltage (VM) is increased and the regenerative power (P ) increases. In this way, during regenerative braking, the amount of generated electric power is always controlled to be the maximum in the current state.

[Problem that the invention seeks to solve]

Since the conventional electric vehicle control method is performed as described above, depending on a change in the power supply voltage, the inverter's overvoltage keeper is activated before the regenerative power control response occurs, and regenerative braking becomes disabled. Therefore, there was a problem in that the regeneration efficiency decreased and air braking had to be used for subsequent operation.

This invention was made to solve the above-mentioned problems, and aims to generate as much regenerative power as possible.1. The purpose of this invention is to obtain a control method for an electric vehicle that prevents the inverter from stopping due to transient fluctuations.

Means for Solving Problems] The electric vehicle control method according to the present invention is such that during regenerative braking control of an induction motor, the power supply side voltage of a variable voltage variable frequency inverter reaches the maximum voltage at which the variable voltage variable frequency inverter can operate. When the voltage approaches the voltage value, the voltage of the induction motor is reduced to suppress the rise in the voltage on the power supply side of the variable voltage variable frequency inverter.
When the increase in the voltage on the W source side of the variable voltage variable same wave number inverter cannot be suppressed, the slip frequency of the induction motor is reduced at a predetermined rate [so that the rate of decrease in the slip frequency is maintained.

[Effect]

The electric vehicle control method according to the present invention improves the efficiency of regenerative braking.

[Actual case]

FIG. 3 shows the characteristics of the induction motor when the value of motor voltage (VM)/inverter frequency in equation (2) is changed.

In the figure, curve (61) is defined as VM/f rNy −k
ax, curve (62) as VM/fINV = k111
2, the slip frequency (fs) is set to f81 by the slip frequency/motor's current characteristics when k2x > k22.
When changing from fs2 to fs2, the change in the same characteristic curve is larger for curve (61) than for curve (62). Conversely, from the point of view of control stability, this means that the curve (62
) is more stable. This is VM/
This is because the change in motor lightning current with respect to the change in fruv is small.

Below, the slip frequency and motor current characteristics are expressed by the curve in Figure 3 (
62) will be explained with reference to the figures. @
In Figure 1, (71) is the overvoltage protection setting value, (+72
) is the motor current throttling start voltage, (73) is the overvoltage suppression limit value, and (8) is the filter capacitor voltage (EF
C) time course curve, (91 is the VM/f of the induction motor (5)
(10) A time curve of the slip frequency (f8), and a time curve of (1υ regenerative output (Pi)).

In Figure 1, when the regenerative load decreases at time 11, the capacitor voltage (81) increases. Therefore, by reducing VM/rBv, the capacitor voltage (8) is prevented from becoming -42 below the overvoltage protection setting value.

At this time, VM/fxuv (g
When + becomes less than the limit value (73), which suppresses overvoltage during voltage transient fluctuations due to load turning on/off,
Control is stabilized by reducing the slip frequency (fs). By kneading, the capacitor voltage (
81 is clamped to the overvoltage protection setting value (γ1). However, overvoltage protection often causes regenerative braking to fail. At time t3, the regenerative load is restored, and then AK and VM/frsv are returned to their original values17, making it possible to increase the amount of regeneration.

By kneading, not only people but also Airmen 11i can increase regeneration efficiency.
11 By reducing the number of blades, it is possible to reduce the wear of the play guishu, etc.

In the above 1f example, when -HVM/fTNV [91+N] falls below the limit value (73) for pressure suppression, fs remains decreased, but V'M/fINvi9) changes when the regenerative load returns. It is also possible to return to

〔Effect of the invention〕

As described above, according to the present invention, as the regenerative load is reduced, the increase in the voltage on the power supply side is reduced by reducing VM/f:[NV, thereby reducing the amount of regeneration, L7 suppresses overvoltage, and increases the amount of regeneration. In a state where there is no Jl, it is possible to stabilize the 8+ control q) by reducing the slip frequency, reduce the loss of regenerative braking, and increase the regenerative load as shown in Figure 1. This improves the efficiency of regenerative braking. I can hope for it.

[Brief explanation of drawings]

FIG. 1 is a curve diagram showing a control method for an electric vehicle according to a practical example of the present invention, FIG. 2 is a control circuit diagram of the electric vehicle, and FIG. 3 is a characteristic curve diagram of a rib conductor. In the figure, ('71) is the overvoltage protection setting value, (T2) Vi motor current 1. Skin pressure at the start of sinking, (73) is the limit value for overvoltage suppression, (8) is the filter capacitor voltage, (91 is the ratio of motor voltage to inverter frequency. In addition, the same symbol in the figure indicates the same - or equivalent part. shows.

Claims (2)

[Claims] (1) In an electric vehicle control method in which an induction motor is controlled by a variable voltage variable frequency inverter, during regenerative braking control of the induction motor by the variable voltage variable frequency inverter,
When the voltage on the power supply side of the variable voltage variable frequency inverter approaches the maximum voltage value at which the variable voltage variable frequency inverter can operate, the voltage of the induction motor is decreased to increase the voltage on the power supply side of the variable voltage variable frequency inverter. and when an increase in the voltage on the power supply side of the variable voltage variable frequency inverter cannot be suppressed, the slip frequency of the induction motor is reduced by a predetermined percentage to maintain the reduction rate of the slip frequency. How to control an electric car. (2) Claim 1 characterized in that when the power supply side voltage of the variable voltage variable frequency inverter becomes lower than a predetermined value, the slip frequency of the induction motor is returned to the value before being reduced.
Method for controlling an electric vehicle as described in section.