JPH0819269A - Method of compensation for on delay of power transistor of servo controller - Google Patents

Abstract

PURPOSE:To compensate the dispersion of the on delay of the power transistor of a servo controller. CONSTITUTION:In the method of compensating the on delay of the power transistor of a servo controller by connecting a plurality of pairs of power transistors corresponding to the number of phases on a power line, and turning off each power transistor, the current command value to be applied to the base of a pair of power transistors of one phase is increased gradually, and the current command value at the time when the load current of that phase begins to flow is sought and it is stored, and this is performed as to each phase, and sought each current command value is used as the on delay command value of each transistor at the time of actual drive.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power transistor on-delay compensation method for a servo controller which performs on-delay compensation of a power transistor.

[0002]

2. Description of the Related Art For example, in a servo control device for driving an AC motor with three phases, six power transistors are combined and a three-phase current is passed through a winding. These power transistors must be alternately driven so that a current flows through the winding at a phase angle (electrical angle) of 2π / 3, but in order to prevent a short circuit in each transistor,
There is a time delay called on-delay, and because it is delayed again,
It is used to compensate for this.

On-delay compensation of a conventional power transistor is, as shown in FIG. 4, in the direction of the current command for each phase.
A certain amount of compensation was added to each phase. However, in such a compensation method, the actual on-delay of each transistor varies, so that a certain amount of compensation causes insufficient compensation or overcompensation, and current does not flow, resulting in oscillation. There was a problem. JP-A-3-135
Japanese Patent No. 389 describes that on-delay compensation is performed according to the magnitude and polarity of the current command signal.

[0004]

However, the method disclosed in Japanese Patent Laid-Open No. 3-135389 cannot compensate for variations in the on-delay of each transistor, resulting in insufficient compensation or overcompensation. there were. Therefore, it is an object of the present invention to perform on-delay compensation for each transistor to compensate for variations in each transistor.

[0005]

In order to solve the above-mentioned problems, a power transistor on-delay compensation method for a servo controller according to the present invention connects a pair of power transistors in a number of phases between power supply lines and connects each power transistor to each other. In the on-delay compensation method of the power transistor of the servo controller that turns on and off at a predetermined phase, the current command value applied to the base of a pair of power transistors of a certain phase is gradually increased, and the load current of that phase is increased. It is characterized in that a current command value at the time of starting the flow is obtained and stored, this is performed for each phase, and each obtained current command value is used as an on-delay compensation value of each transistor during actual driving. . As another compensation method, one of a pair of power transistors of a certain phase is continuously ignited, the ignition time of the other is extended, and the time when the current flows out is obtained.
It is also possible to perform this for each phase and use each current command value corresponding to each obtained time.

[0006]

By the above means, the compensation is performed in accordance with each transistor, so that it is possible to prevent the torque from not being produced due to the insufficient compensation, and to prevent the vibration due to the over compensation.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A concrete embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a circuit diagram showing the configuration of an embodiment of the present invention, and FIG. 2 is a flow chart showing the operation. In FIG. 1, 1 is a diode bridge, 2 is a main capacitor, 3 is a power transistor, 4 is a microcomputer, 5 is a base drive circuit, and 6 is a current detector.

The operation of the on-delay compensating circuit configured as above will be described with reference to the flowchart of FIG.
First, in step 10, the main power supply is turned on and a DC voltage is charged between PN. Next, in step 20, a positive current command is applied to the U phase and a negative current command is applied to the V phase to increase the current command, and the current detector 6 determines the current command to flow out, and the current command in the microcomputer 4 is calculated. Store in memory.
At this time, the U phase of the current command is i _uo and the V phase is i _v1 . In step 30, similarly to step 20, a positive current command is applied to the V phase and a negative current command is applied to the W phase to obtain current commands i _V0 and i _w1 that flow out. Step 40 is also Step 20,
Similarly to 30, the current commands i _w0 and i _u1 that flow out are obtained. In step 50, the on-delay compensation values i _u0 , i _u1 , i _v0 , i _v1 , i _w0 , and i _w1 of each transistor are set. i _u0
Is the U-phase upper transistor and i _u1 is the on-delay compensation value of the U-phase lower transistor. For example, in the case of a positive current command for the U phase and a negative current for the V, W phases, U, V, W
On-phase compensation is performed by adding i _u0 , i _v1 , and i _w1 to the phase to the current command. In this way, the on-delay of each transistor is observed and set.

Further, instead of the current command, the power transistor may be ignited for a certain period of time, the ignition time may be extended, and the ignition time at which the current starts flowing may be determined and set as a compensation value. . FIG. 3 is a flowchart showing the example. This means that one of the upper and lower transistors of each phase forming a conductive pair is continuously ignited, the ignition time of the other is extended, and the current starts to flow t _u0 , t _v1 , t.
_v0 , t _w1 , t _w0 , and t _u1 are obtained, and from these values, the on-delay compensation current command value is set based on the following equation. i = i _sat × f × (firing time) where _isat : saturation current command value f: transistor switching frequency [Hz] i: on-delay compensation current command value

[0010]

As described above, according to the present invention, since the compensation value is obtained and compensated for each transistor, the variation of each transistor can be absorbed and the compensation can be surely performed. Further, if the compensation value is obtained when the current is applied, it is possible to suppress the deviation of the compensation value due to aging. As a result, it is possible to prevent current shortage due to insufficient compensation and excessive current due to overcompensation.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a specific embodiment of the present invention.

FIG. 2 is a flowchart showing the operation of the on-delay compensation circuit according to the present invention.

FIG. 3 is a flowchart showing another method of on-delay compensation according to the present invention.

FIG. 4 is a circuit diagram showing a conventional example of on-delay compensation.

[Explanation of symbols]

1 diode bridge, 2 main capacitors, 3
Power transistor, 4 microcomputer, 5 base drive circuit, 6 current detector

Claims (2)

[Claims] 1. An on-delay compensation method for a power transistor of a servo controller for connecting a pair of power transistors in a number of phases between power supply lines and driving the power transistors by turning them on and off. Gradually increase the current command value applied to the base, find and store the current command value when the load current of that phase begins to flow, and perform this for each phase. Is used as an on-delay compensation value of each transistor at the time of actual driving, a power transistor on-delay compensation method for a servo controller. 2. An on-delay compensation method for a power transistor of a servo controller for connecting a pair of power transistors in a number of phases between power supply lines and driving the power transistors by turning them on and off. Continue firing one side and extend the firing time of the other side, find the time when the current starts to flow, do this for each phase, and compensate the on-delay compensation of each transistor with the current command value corresponding to each found time. A power transistor on-delay compensation method for a servo controller, which is used as a value during actual driving.