JPH01283016A - Current controller for motor - Google Patents

Abstract

PURPOSE:To improve reliability and safety by producing an alarm and interrupting a circuit when the source voltage of a control circuit is abnormal. CONSTITUTION:Current being fed from a power amplifying section 4 to a motor 7 is detected through shunt resistors 5a, 5b and fed through insulation amplifiers 6a, 6b, a switch 3 and an A/D converter to CPU 1 where it is monitored. In the invention, voltages to be applied from power sources 9a, 9b to a control circuit are read in by the CPU 1 through a switch 8 and an A/D converter 2. An alarm is produced and a gate interruption signal is fed to the power amplifying section 4 in case of abnormal source voltage.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a current control device for a motor that controls the current supplied to the motor, and particularly relates to a current control device for a motor that controls the current supplied to the motor, and particularly to prevent failures in the current detection section and abnormalities in the control power supply used for current detection. It performs protective operations in response to

[Conventional technology]

FIG. 7 is a block diagram showing a conventional electric motor current control device. In the figure, (1) is a CPU that performs servo processing;
(2) is an AD converter that converts the current value converted into voltage into digital data, (3) is a switch for selecting the channel of the AD converter, (4) is the power amplifier, and (5a) is the U phase. Shunt resistor for current detection, (5b
) are shunt resistors for V-phase current detection, (6a), (6b)
is an isolation amplifier for insulating the detected voltage (current value) of each phase, and these (1) to (6a) and (6b) constitute a control circuit. Further, (7) is a driving electric motor.

Next, the operation will be explained. First, with the gate of the power amplifier (4) cut off (current is not flowing), the current feedback channel switch (3) is selected for the U and V phases to set the current offset amount. At this time, failures in the current detection section are detected by monitoring whether abnormal data is detected at the same time. Power amplification section (
After the gate of 4) becomes electric, the current flowing through the electric motor (7) is converted into voltage by shunt resistors (5a) (5b), and then proportional to the current value by insulation amplifiers (6a) (6b). This voltage is created based on the ground of the control circuit, so by switching the channel with an analog switch, it is converted into a digital amount by the AD converter (2), and the CPU (1) performs current loop processing and power amplification. A command is output to section (4).

While the electric motor is being driven, current is constantly flowing, so the above monitoring is not possible.

[Problem to be solved by the invention]

Conventional current control devices are configured as described above, so even if a failure occurs in the current detection unit for some reason while the motor is being driven, an alarm will be generated because it cannot be detected that this is a failure of the element or power supply. There were problems such as delays in the activation of protection functions due to outbreaks, etc., and destruction of control equipment.

This invention was made to solve the above-mentioned problems, and it is possible to constantly monitor failures in the elements of the current detection section and the control power supply, and to immediately take protective action in the event of a failure. The purpose is to obtain a current control device for an electric motor.

(Means for Solving the Problems) A current control device for a motor according to the present invention detects a current supplied to the motor from a power amplification section, converts the detected current into digital data using an AD converter, and supplies it to a CPU. A current control device for a motor includes a control circuit that issues a control command to the power amplifying section to control the current supplied to the motor, and a control power supply potential detection circuit that detects a power supply potential of the control circuit is provided. When the power supply potential exceeds a predetermined range, an alarm output is sent out based on the CPU, and a gate cutoff command is issued to the power amplification section.

(Function) The current control device according to the present invention is provided with a means for detecting the power supply potential of the control power source in the current detecting section of the control circuit. It is possible to monitor abnormalities in the control power supply and provide protection in the event of an abnormality.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. 7th
In FIG. 1, parts that are the same as those shown in the figure are given the same reference numerals. In FIG. Indicates the power supply for detection, and the power supply potential detection circuit (8)
When the power supply potential detected by
(1) Based on the given CPII (1) D, an alarm output is sent out and a gate cutoff command is issued to the power amplification section (4).

Here, the sampling period of the power supply potential detection based on the analog switch (3) and the power supply potential detection circuit (8) by the CPU (1) is, for example, the sampling period of the U phase and the ■ phase is every processing period T of the current control loop. The sampling of the power supply potential detection circuit (8) is performed at a slightly larger period T2 (for example, once every four current control loop processes).

The basic method of detecting current is the same as the conventional method. In this embodiment, as shown in the flowchart of FIG.
After sampling the phase and ■phase currents, the channel is switched to the power supply potential detection circuit (8), and the voltage is detected by the to〇 converter (2).

Now, let this be V (VP, VN). This value is the detection error tolerance V a+ln~vmax (VPIII
II≦vp≦vP la a X *VNmln≦vN
≦vNIla+c) is checked each time, and V > Vaaax or V < Veat n
(see Figure 3), the current detection unit, that is, the AD
It is assumed that a failure has occurred in the converter (2) or the current detection power supply (9) for some reason, and the CPU (1)
As a result, the current current value is invalidated, and furthermore, as shown in FIG. 3, an alarm is generated, the gate of the power amplifying section (4) is cut off, and protective operations such as turning off the converter power are performed.

Note that input malfunction of the AD converter (2) due to noise etc. may result in V > V, , You can do it as you like.

Therefore, according to the above embodiment, it is possible to monitor malfunctions of the current detection section and abnormalities of the control power supply used therein.

Next, FIG. 4 shows another embodiment of the present invention, which differs from the embodiment in FIG. °) for current detection! (9a), (
9b) does not exist.

In this embodiment, the ground potential detection circuit (8
2), it is possible to monitor abnormal operation of the current detection section, especially the AD converter, and provide protection in the event of abnormality.

That is, when the ground potential detected by the ground potential detection circuit (8°) deviates from a predetermined range, the detection signal is given to the CPU (1) via the AD converter (2), and an alarm is issued based on the CPU (1). At the same time as output is sent out, a gate cutoff command is issued to the power amplifier section (4).

The basic method of detecting current is the same as the conventional method. In this embodiment, as shown in the flowchart of FIG.
After sampling the phase and -phase currents, the channel is switched to the ground potential detection circuit (8°), and the voltage thereof is detected by the AD converter (2). Now this is V. shall be. Then, it is checked every time whether this value exceeds the detection error tolerance value V□8, and when it reaches 1 VaDV, x (6th
(see figure) is the current detection section or AD converter (2)
Alternatively, it is assumed that a failure has occurred in the current detection power supply (9) for some reason, and the current current value is invalidated by CPt1 (1). Furthermore, as shown in Figure 6, an alarm is generated and the power amplification is performed. In addition to cutting off the gate of section (4), protective operations such as turning off the converter power are performed.

Note that since 1vo1>v,x may occur due to input malfunction of the AD converter (2) due to noise or the like, the protective operation may be performed after detecting that this condition has occurred several times.

Therefore, according to the above embodiment, it is possible to monitor malfunctions of the current detection section, particularly abnormalities of the AD converter.

(Effects of the Invention) As described above, according to the present invention, it is possible to monitor malfunctions of the current detection section and abnormalities of the control power supply used therein, so that a product with extremely high reliability and safety can be obtained. There is.

[Brief explanation of the drawing]

FIG. 1 is a block diagram according to an embodiment of the present invention, FIG. 2 is a flowchart showing the processing contents of the present invention, FIG. 3 is an operation sequence diagram of the present invention, and FIGS. 1 to 3, and FIG. 7 is a hardware block diagram showing a conventional current detection section. In the figure, (1) is the CPU, (2) is the AD converter, (4
) is a power amplification section, (5a) and (5b) are shunt resistors for current detection, (7) is a motor, (8) is a power supply potential detection circuit, (8゛) is a ground potential detection circuit, (9a), (
9b) is a power supply for current detection. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] The current supplied to the motor from the power amplifier is detected, and the detected current is digitally converted by the AD converter and sent to the CPU.
A control power supply potential detection circuit for detecting a power supply potential of the control circuit in a current control device for a motor, comprising a control circuit that issues a control command to the power amplifying section to control the current supplied to the motor by giving a current to the motor. 1. A current control device for a motor, comprising: a current control device for a motor, wherein when a detected power supply potential deviates from a predetermined range, an alarm output is sent out based on the CPU, and a gate cutoff command is issued to the power amplification section.