JP2002315346A - Monitoring method for cpu computation time in power converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To monitor the CPU computation time in a power converter online, and if the computation time is determined as being abnormal, output pulses is interrupted and further, inform a higher-level processor is informed of that. SOLUTION: A method for monitoring the computation time in the power converter involves a PWM data computing means 2, which calculates the output voltage command according to a frequency command received from a higher- level processor 1 and calculates the degree of modulation of signal waves corresponding to the fundamental wave component of output voltage from the frequency command and the output voltage command and a phase angle which advances by each cycle of carrier waves that is used as the basis of switching, and a PWM pulse generating means 3 which calculates the pulse width of PWM pulses, based on the degree of modulation; and the phase angle which are the output of the computing means and generates PWM pulses. The CPU computation time for the PWM data computing means is monitored by the PWM pulse generating means 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for monitoring a CPU operation time of a power converter for driving an electric motor.

[0002]

2. Description of the Related Art As a method of monitoring the CPU operation time of a power conversion device, a method of monitoring the operation of a pulse generating means for generating a pulse signal based on a result of the calculation and a pulse width of a PWM pulse can be considered. JP-A-6-1
No. 69575. In the above publication, the operation means and the pulse generation means are constituted by two microcomputers which operate independently of each other, so that the operation of the operation means and the pulse generation means is monitored, and when it is determined that the operation is abnormal, the output is outputted. The pulse is stopped and the host processor is notified.

[0003]

However, in the above-mentioned publication, since it is composed of two microcomputers, the CPU operation time of the power conversion device to meet the market needs for miniaturization and price reduction in the miniature light machine market. There was a problem that it was not appropriate as a monitoring method. further,
Since the CPU processing time is not notified to the upper processing unit, C
There is a problem that the PU operation time cannot be monitored online or trace-back for failure diagnosis cannot be performed. Therefore, the present invention comprises a single microcomputer to monitor the CPU operation time on-line, notify the CPU operation time to a higher-level processing device, and output an output pulse when it is determined to be abnormal. And to notify a higher-level processing device.

[0004]

In order to solve the above-mentioned problems, the present invention calculates an output voltage command according to a frequency command received from a host processor, and calculates a fundamental wave of an output voltage from the frequency command and the output voltage command. PWM data calculating means for calculating a modulation degree of a signal wave corresponding to a component and a phase angle which advances every one cycle of a carrier wave serving as a reference for switching, and a PWM based on the modulation degree and the phase angle which are outputs of the calculating means.
Calculate the pulse width of the pulse to generate a PWM pulse
In the method for monitoring the operation time of a power conversion device provided with a WM pulse generation means,
A CPU operation time monitoring method for a power converter, wherein the CPU operation time of an M data operation unit is monitored. The PWM data calculation means calculates the CPU calculation time of the PWM data calculation means by reading the count value of the watchdog timer means at the start and end of the calculation, and notifies the PWM pulse generation means of the CPU calculation time. 2. The method according to claim 1, wherein a notification is sent to a host processor. The PWM pulse generation means is a PWM data calculation means.
The PU operation time is monitored, and when the CPU operation time is out of a predetermined time range, the PWM data operation means is determined to be abnormal, the output pulse of the PWM pulse generation means is cut off, and 2. The method according to claim 1, wherein the notification is sent to the CPU. 2. The power conversion apparatus according to claim 1, wherein the PWM data calculation means clears the count value of the watchdog timer means immediately after reading the count value of the watchdog timer means at the end of the calculation. CPU calculation time monitoring method. When the count value of the watchdog timer means is larger than a predetermined count value set in advance, the PWM data calculation means is determined to be abnormal, and the output pulse of the PWM pulse generation means is cut off. 2. The method according to claim 1, wherein the notification is sent to the CPU. 2. The power conversion device according to claim 1, wherein the PWM data calculation unit and the PWM pulse generation unit are configured by one microcomputer.
PU operation time monitoring method. PWM data calculation means, PWM
2. The method according to claim 1, wherein the pulse generator and the watchdog timer are configured by a single microcomputer.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a system configuration for explaining a CPU operation time monitoring method of the present invention. 1 is a higher-level processing device such as a sequencer, 7 is a motor, 6 is a main circuit of a power converter for controlling the motor, 5 is a gate drive circuit, 8 is a PWM pulse generating means 3, a PWM data calculating means 2, and a watchdog. It is a microcomputer including timer means 4. The power converter includes a main circuit 6, a gate drive circuit 5, and a microcomputer 8. In the figure, power supplies such as a power supply voltage and a control power supply are omitted. The PWM pulse generating means 3 includes a PWM pulse width calculating means 3-1 and a PWM pulse output setting means 3-2.
And PWM pulse output cutoff means 3-3 and CPU operation time monitoring means 3-4. Next, the PWM data calculation means 2 comprises an input / output interface 2-1, an output voltage command calculation means 2-2, a signal wave calculation means 2-3, and a CPU calculation time calculation means 2-4.

[0006] The present system uses a P which controls the power converter.
It is a host processor 1 such as an LC (Program Logic Controller sequencer) or an operation panel, and outputs a frequency command to a power converter such as an inverter. The processing device 1
, And calculates a modulation degree 14 of a signal wave corresponding to a fundamental wave component of an output voltage and a phase angle 15 advancing every one cycle of a carrier serving as a switching reference, and a CPU calculation time 11. The PWM data calculating means 2 calculates the PWM pulse width based on the modulation factor 14 and the phase angle 15 output from the PWM data calculating means 2 to generate a PWM pulse 19 and the PWM data calculating means PWM pulse generating means 3 for monitoring the CPU calculation time 11 output from the CPU 2, watchdog timer means 4 for monitoring the operation of the PWM data calculating means 2, and P output from the PWM pulse generating means 3.
The gate drive circuit 5 drives the electric motor 7 by switching the power semiconductor elements of the main circuit 6 according to the WM pulse 19. PWM data calculation means 2, PWM
M pulse generating means 3 and watchdog timer means 4
Is composed of one microcomputer 8.

The host processor 1 is a PLC (sequencer), an operation panel, or the like, calculates the speed of the electric motor 7, and outputs a frequency command signal 10 corresponding to this speed to the P.
It outputs to the input / output interface 2-1 of the WM data calculation means 2. Further, the processing device 1 determines that the CPU operation time 11 output from the input / output
The PU abnormality notification 12 is inputted, such information is monitored on a display device, or stored as traceback data for failure diagnosis. The PWM data calculation means 2 comprises:
An output voltage command calculating means 2-2 for calculating an output voltage command 13 corresponding to the frequency command signal 10 input via the input / output interface 2-1; output from the frequency command signal 10 and the output voltage command 13; A signal wave calculating means 2-3 for calculating a modulation degree 14 of a signal wave corresponding to a fundamental wave component of a voltage and a phase angle 15 advancing every one cycle of a carrier wave serving as a reference for switching; the watchdog timer means 4
The CPU calculation time of the PWM data calculation means 2 is calculated by reading the count value 16 of
The PU operation time 11 is output to the PWM pulse generating means 3 and the input / output interface 2-1, and a count clear signal 17 for clearing the count value of the watchdog timer means 4 within a predetermined time limit is output. And CPU operation time calculation means 2-4.

[0008] The PWM pulse generating means 3 outputs the PWM pulse
PWM for calculating the pulse width of a PWM pulse based on the modulation degree 14 and the phase angle 15 output from the M data calculating means 2
The PWM pulse width data 18 output from the pulse width calculating means 3-1 and the PWM pulse width
A PWM pulse output setting means 3-2 for outputting an M pulse 19 to the external gate drive circuit 5;
PWM pulse output cutoff means 3-3 which can prevent the PWM pulse 19 output from the pulse output setting means 3-2 from being output to the gate drive circuit 5,
If the CPU calculation time 11 output from the PWM data calculation means 2 is not within a predetermined time range, the PWM
In order to determine that the M data calculation means 2 is abnormal, and to prevent the PWM pulse 19 from being output to the gate drive circuit 5, the PWM pulse output cutoff means 3-3 outputs the PWM pulse 19 to the PWM pulse output cutoff means 3-3.
The M pulse output cutoff signal 20 is output and the CP
It comprises a CPU calculation time monitoring means 3-4 for outputting a U abnormality notification 12 to the input / output interface 2-1. The watchdog timer means 4 controls the PWM data calculation means 2 within a predetermined time limit after the count is started.
When the count clear signal 17 is not received from
That is, when the count value becomes larger than the predetermined count value, the PWM data calculation means 2 is determined to be abnormal, and the PWM pulse 19 is transmitted to the gate drive circuit 5.
In order to prevent the output from being output to the PWM pulse output cutoff means 3-3, the PWM pulse output cutoff signal 20 is output to the PWM pulse output cutoff means 3-3, and the CPU abnormality notification 12 is sent to the power converter via the input / output interface 2-1. Output to the operation panel, the PLC or the host controller 1.

Hereinafter, the processing method of the CPU operation time monitoring method of the present invention will be described in detail. The PWM data calculation means 2 sets C at every predetermined period (for example, every 5 msec).
Processing is performed by an interrupt program (LOW scan program) executed by the PU. The PWM pulse generating means 3 includes:
Processing is performed by an interrupt program (HIGH scan program) executed by the CPU every predetermined cycle (for example, every 100 μsec). The watchdog timer means 4 comprises:
The count is started immediately before the LOW scan program is initially started. If the count clear signal 17 is not received from the CPU operation time calculation means 2-4 within a predetermined time limit (for example, within 6 msec) after the count is started, that is, the count value becomes larger than the predetermined count value. The PWM
The data calculation means 2 is determined to be abnormal, and the PWM pulse 1
9 to prevent the PWM pulse output from being output to the gate drive circuit 5.
A pulse output cutoff signal 20 is output and the CPU
An abnormality notification 12 is output to the input / output interface 2-1.

FIG. 2 shows a flowchart of the LOW scan program. F1 is a processing block for reading the count value 16 of the watchdog timer means 4 at the start of the LOW scan program and storing the count value 16 in the work RAM 1. F2 is a processing block for performing a predetermined PWM data operation. F3
Reads the count value 16 of the watchdog timer means 4 at the end of the LOW scan program,
This is a processing block for storing the count value 16 in the work RAM 2. F4 is the work RA from the work RAM2.
M1 is subtracted, and the result of the subtraction is referred to as the CPU operation time 1
1 is a processing block to be stored. F5 is a processing block that outputs the count clear signal 17. The CPU operation time 11 is determined by the input / output interface 2-
At 1 the count is converted from the unit of count to the unit of msec and output to the processing device 1. The HIGH scan program includes a processing block of the CPU calculation time monitoring unit 3-4. The processing block reads the CPU calculation time 11 stored in the processing block F4,
The CPU calculation time 11 is within a predetermined time range (for example, 4.5 msec or more and 5.5 msec).
If it is not within the following time range), the PWM data calculating means 2 is judged to be abnormal, and the PWM pulse output cut-off means 3- 3 and outputs the PWM pulse output cutoff signal 20 and the CPU abnormality notification 12 to the input / output interface 2-1.

In this embodiment, the PWM data calculating means, the PWM pulse generating means and the watchdog timer means are constituted by one microcomputer, but the PWM data calculating means and the PWM
The pulse generating means may be constituted by one microcomputer, and the watchdog timer means may be an external circuit.

[0012]

As described above, according to the present invention, the CP is constituted by one microcomputer.
In addition to monitoring the U operation time, the CPU operation time is notified to a higher-order processing device, and when an abnormality is determined, the output pulse is cut off and the higher-order processing device can be notified. There is.

[Brief description of the drawings]

FIG. 1 is a diagram showing a system configuration for explaining a CPU operation time monitoring method of the present invention.

FIG. 2 is a diagram showing a flowchart of a LOW scan program.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 High-order processing apparatus 2 PWM data calculation means 3 PWM pulse generation means 4 Watchdog timer means 5 Gate drive circuit 6 Main circuit, 7 Motor, 8 Microcomputer 2-1 I / O interface 2-2 Output voltage command calculation means 2- Reference Signs List 3 signal wave calculation means 2-4 CPU calculation time calculation means 3-1 PWM pulse width calculation means 3-2 PWM pulse output setting means 3-3 PWM pulse output cutoff means 3-4 CPU calculation time monitoring means 10 frequency command signal 11 CPU calculation time 12 CPU error notification 13 Output voltage command 14 Modulation degree 15 Phase angle 16 Count value 17 Count clear signal 18 PWM pulse width data 19 PWM pulse 20 PWM pulse output cutoff signal

Claims (7)

[Claims] An output voltage command is calculated in accordance with a frequency command received from a host processor, and the frequency command and the output voltage command serve as a modulation factor of a signal wave corresponding to a fundamental wave component of an output voltage and a reference for switching. PWM data calculating means for calculating a phase angle which advances in each cycle of a carrier wave, and PWM based on the modulation degree and the phase angle which are outputs of the calculating means.
Calculate the pulse width of the pulse to generate a PWM pulse
In the method for monitoring the operation time of a power conversion device provided with a WM pulse generation means,
A CPU operation time monitoring method for a power converter, wherein the CPU operation time of an M data operation unit is monitored. 2. The PWM data calculation means calculates the CPU calculation time of the PWM data calculation means by reading the count value of the watchdog timer means at the start and end of the calculation, and calculates the CPU calculation time by a PWM pulse. 2. The method according to claim 1, further comprising notifying the generating means and notifying the host processing device. 3. The PWM pulse generation means monitors a CPU calculation time of the PWM data calculation means, and determines that the PWM data calculation means is abnormal when the CPU calculation time is out of a predetermined time range. 2. The method according to claim 1, wherein the output pulse of the PWM pulse generating means is cut off and notified to a host processing device. 4. The PWM data calculation means according to claim 1, wherein said PWM data calculation means clears the count value of said watchdog timer means immediately after reading the count value of said watchdog timer means at the end of the calculation. A method for monitoring CPU operation time of a power converter. 5. When the count value of the watchdog timer means is larger than a predetermined count value set in advance, the PWM data calculation means is determined to be abnormal, and the output pulse of the PWM pulse generation means is cut off. 2. The method according to claim 1, wherein a notification is sent to a host processing device. 6. The CP of the power converter according to claim 1, wherein the PWM data calculation means and the PWM pulse generation means are constituted by one microcomputer.
U operation time monitoring method. 7. The microcomputer according to claim 1, wherein said PWM data calculation means, said PWM pulse generation means, and said watchdog timer means comprise one microcomputer.
3. The method for monitoring CPU operation time of a power converter according to claim 1.