JPH04125090A - Controlling method for power converter of vehicle - Google Patents

Abstract

PURPOSE:To prevent deterioration of idling, at the time of idling by compensating the delay of a rotating speed by its differentiation, and connecting an idle control term for operating reverse characteristic to a rotating speed presuming term in series at the time of idling with the rotating speed presuming term. CONSTITUTION:An idle sense control term in which presuming term is output as reverse characteristic is associated at the time of idling, and sum with an IM rotating speed is obtained. A command frequency is obtained by the sum of command slip frequency and filter capacitor voltage differentiating term and a term of detecting the rotating speed. The delay time of detecting the rotating speed of the IM is compensating by differentiating at the time of gliding to presume a rotating speed near the actual speed. The rotating speed at the time of idling becomes faster than that at the time of gliding. However, since a slip command is constant, as the rotating speed increases, a command frequency is increased to accelerate a rotation. Thus, the rotting speed presuming term is operated reversely to the rotating speed to reduce the command frequency at the time of idling to prevent an increase in the idling.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a method for controlling a power converter for a vehicle.

(Prior Art) A vehicle obtains power for a three-phase squirrel cage induction motor (hereinafter referred to as IM), which is a power source of the vehicle, through a vehicle power converter. This vehicle power converter converts high overhead line voltage into a voltage and frequency suitable for the IM, which is the load, and controls the IM.

As an example, a case where an inverter is used in a power conversion device will be described. FIG. 2 is its circuit diagram. Inverter circuit 4 connects pantograph 1 to DC filter reactor 2
Connect via. Further, the DC filter capacitor 3 is connected in parallel to the DC input terminal of the inverter circuit 4. Then, the IM is connected to the three-phase AC output of the inverter circuit.

As shown in Figure 3, a three-phase induction motor has three sets of coils arranged symmetrically around the surface of a cylindrical stator core, and when a symmetrical three-phase alternating current is applied, a rotating magnetic field is generated according to Fleming's left-hand rule. If the phase rotation of three-phase alternating current is A, B, and C, then
N that forms in the void.

The magnetic field of S rotates in the same direction of the arrow as the phase rotation, and its rotation speed is Ns= 12Of-[rpH] 2 ...... ■ P
: Number of poles f: Frequency (Hz) Ns two synchronous speed (rpm). A current flows through the conductor of the rotor due to the electromagnetic induction effect of this rotating magnetic field, and this current and magnetic field generate an electromagnetic force in the conductor, which becomes a rotational force with respect to one rotor axis. The rotational speed of the rotor is slower than the synchronous speed, but there is a value S that represents this degree.

Slip is expressed as the ratio of the amount by which the rotational speed decreases from the synchronous speed to the synchronous speed, and the slip at the rotational speed N (rpm) is 3=N"L...■S. One rotational speed is ω=2π・1. (rad/s), and when N and ω are expressed by S, 20f N= N5(1-3)= (1-3) (
rpm) -■Also c, +=2π"yo="f(1-5)
(rad/s)-m60P.

And the torque TAN-■] of the rotating machine is T = Pm = 60Pm = PoPm (N-
,) ,・, ■ω 2πN r■πdrunk Pa: Output of the rotating machine PmCν] Also, Pa+:=P, (1-9) (W) P2: When it is assumed that it rotates at a synchronous speed with the secondary input The output is [synchronous watts].

As shown in the 0-0 formula, the torque and rotational speed can be changed by changing the IM speed and frequency.

In this way, IM can be controlled by the frequency provided by the inverter device. A control block diagram thereof is shown in FIG.

The command slip in order of command slip frequency is a command value determined by the torque to be output from the IM. The rotational speed prediction term detects the rotational speed of the IM and determines the rotational speed on the rotor side.

The filter capacitor voltage differential term detects a sudden rise in the overhead line voltage and reflects it in the control so that the output voltage of the inverter does not suddenly rise when the overhead line voltage rises suddenly.

Furthermore, the rotational speed detected from equation 0 is slower than the synchronous speed by the amount of slip. Therefore, in order to keep the rotational speed constant, a frequency for rotating the stator at a synchronous speed is commanded based on the sum of the detected rotational speed and the command slip. In addition, a filter capacitor voltage differential term is added to the control in case of sudden changes in the overhead line.

(Problem to be Solved by the Invention) The rotational speed of a pulse sensor type IM is determined by counting pulses output from a pulse sensor installed on the motor shaft for a certain period of time. Therefore, when used for control, there is a delay of more than a certain time for calculating the rotational speed. However, since the command slip is a constant value determined by the command, if the delayed rotational speed of the IM is used for control, the command frequency may be different from the slip actually required for the motor. For example, when the rotational speed of the IM oscillates due to the mechanical system natural vibration of the five bogies or the electric system natural vibration of the main circuit, the filter capacitor voltage fluctuates. At this time, an error occurs between the actually required slip and the delayed slip as shown in FIG. As a result, the IM command frequency oscillates, and the torque also oscillates, as shown in formula 0. This vibration resonates with the natural vibrations of the bogie and the main circuit, stopping the inverter and preventing normal operation of the electric vehicle.

By predicting the rotation speed and compensating for the delay time caused by the detection of the rotation speed of the IM, the operation can be brought closer to real-time processing.

[Configuration of the Invention (Means for Solving the Problems) A block diagram of the present invention is shown in FIG. The rotation speed prediction term that compensates for the delay caused by the rotation speed detection calculation of the IM by differentiating the rotation speed and predicts the rotation speed without delay time, and the idle control term that acts with the opposite characteristics to the rotation speed prediction term when idle is connected in series. By connecting, the delay time is compensated and the rotational speed of the IM is predicted by the sum of the rotational speed of the conventional IM.

(Function) Since the rotational speed of the IM is determined by the number of input pulse counts in a certain period of time, the time required for pulse counting and calculation is at least delayed. By compensating for this delay by differentiation, a rotation speed closer to the actual rotation speed can be obtained. When idling, the rotational speed is faster than when sliding, so the IM command frequency increases and the I
Try to rotate M. To prevent this, the command frequency is reduced using the rotational speed prediction term when idling is detected.

(Example) An example of the present invention is shown in FIG. Rotation speed detection uses a rotation speed prediction term that predicts the rotation speed by differentiating the detected rotation speed, and when sliding, this prediction term is output as is, and when idling,
This prediction term is combined with a slip detection control term that outputs an inverse characteristic, and is configured to be summed with the IM rotation speed.

Then, the command frequency is obtained by the sum of the conventional command frequency, the filter capacitor voltage differential term, and the term detected by this rotational speed.

During skidding, a rotation speed close to the actual rotation speed is predicted by compensating for the delay time in detecting the rotation speed of the IM by differentiating the rotation speed prediction term.

Also, when spinning, the rotational speed is faster than when sliding. However, since the slip command is constant, as the rotation speed increases,
The command frequency also increases to further accelerate the rotation. Therefore,
In order to reduce the command frequency at the time of idling, the rotational speed prediction term acts on a characteristic opposite to the rotational speed to prevent further idling.

By correcting the delay time, it is possible to prevent the natural vibration (resonance phenomenon) of the bogie caused by the difference between the delay slip and the actual slip as shown in FIG. 4 to be prevented. Furthermore, when detecting the rotational frequency, the longer the counting time, the smaller the error in rotational speed detection. This is because if a counting error occurs when detecting in a short period of time, the error will be much larger than in the case of a long period of time because it is calculated by counting over a certain period of time. With this prediction, even if the delay time is long, the delay can be corrected and a rotation speed with less error can be used for control.

When idling is detected, a rotation speed higher than the command due to idling is detected, but the idling control term acts to prevent the command frequency from rotating, so that the idling does not worsen.

In this way, the delay time is corrected when skidding, and when the vehicle is idling, it does not worsen.

A similar effect can be obtained even when used in a speed calculation method for an electric vehicle that uses a motor other than an induction motor whose rotational speed is counted by a pulse sensor.

〔Effect of the invention〕

When skidding, the IM's rotational speed delay is corrected, and when it is idling, the rotational speed is predicted to prevent the IM from getting worse. This provides control without delay.

[Brief explanation of drawings]

Fig. 1 is a control block diagram of the present invention, Fig. 2 is a main circuit configuration diagram using an inverter as a power converter, Fig. 3 is an explanatory diagram of the rotating magnetic field of a three-phase induction motor, and Fig. 4 is a conventional block diagram. , FIG. 5 is an explanatory diagram of a slip with a delay. 1... Pantograph, 2... Input DC filter reactor, 3... Input DC filter capacitor, 4... Inverter circuit, 5... Three-phase squirrel cage induction motor.

Claims (1)

[Claims] In a vehicle power converter using an induction motor, a rotation speed prediction term that compensates for the delay time that occurs when a pulse sensor detects the rotation speed of a three-phase squirrel cage induction motor as a load by differentiating the pulse sensor input, and this prediction The rotational speed fluctuation is predicted by the term and the idling control term provided to prevent idling during idling, and the real-time rotational speed is predicted by the sum with the conventional rotational speed with a delay time. A method for controlling a power converter for a vehicle characterized by rotational speed detection.