JP2003088173A - Motor controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a half-bridge PWM motor controller using a bipolar power supply, wherein delay in time between the drawing of motor current and the output of motor voltage is substantially completely eliminated, and thus motor current is controlled with stability in any case, including a case where a high- response motor is adopted. SOLUTION: A PWM converting portion which draws motor current and performs current computation to calculate a motor voltage command is constituted to a positive PWM converting portion and a negative PWM converting portion arranged in parallel. A change-over switch is actuated by a signal indicating the result of judgment of the polarity of motor current to select and change the outputs of the positive PWM converting portion and the negative PWM converting portion. Thus, the period from the time when voltage is applied to a motor to the time when motor current is drawn is equalized both on the positive side and on the negative side. As a result, control characteristics are the same both on the positive side and on the negative side, and the current of the motor can be controlled with stability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brush motor current control, and more particularly to a half bridge P using a bipolar power source.
The present invention relates to a WM (Pulse-Width Modulation) motor control device.

[0002]

2. Description of the Related Art An outline of a conventional motor control device of this type will be described with reference to FIGS. FIG. 5 is a control circuit diagram of a half bridge circuit using a bipolar motor bipolar power source, FIG. 6 is a functional block diagram of a motor control device,
FIG. 7 is an explanatory diagram showing the control timing of the motor control device.

In the conventional motor control device of this type, the electric power applied to the motor 36 is turned on / off alternately between the positive side switch 32 and the negative side switch 33 during one PWM cycle.
The voltage applied to the motor 36 is controlled by the average of the positive power supply 34 and the negative power supply 35.

The positive side switch 32 and the negative side switch 3
The ON / OFF control of No. 3 is performed by the positive side switch drive signal 7 and the negative side switch drive signal 8 shown in FIG.

That is, based on the clock signal 12, P
Among the current calculation timing signal 9 and the PWM timing signal 10 transmitted from the WM cycle timer 11, the motor current 1 is taken into the current calculation unit 3 under the control of the current calculation timing signal 9, and from the motor current 1 and the current command 2. The motor voltage command 4 is calculated.

The motor voltage command 4 is applied to the PWM converter 5, and the PWM converter 5 controls the PWM timing signal 10 to drive the switch P according to the voltage command.
The WM signal 6 is calculated, and the switch drive PWM signal 6 is separated into a positive side switch drive signal 7 and a negative side switch drive signal 8, and the positive side switch drive signal 7 and the negative side switch drive signal 8 are the positive side. The side switch 32 and the negative side switch 33 are controlled.

In the motor 36, "positive" and "negative" voltages are applied to the "positive" of the motor current 1 in synchronization with the PWM timing 21 at a duty corresponding to the motor voltage command 4 calculated by the current calculation unit 3. From "Positive" to "Negative" regardless of "Negative"
The voltage is applied in this order.

Here, the same motor voltage command is applied when a "positive" voltage is applied when the motor current 1 is "positive" and when a "positive" voltage is applied when the motor current 1 is "negative". However, there is a difference in the response of the motor current 1.

[0009]

However, in the above-described conventional motor control device, since the motor current is taken in at a fixed current take-in timing 29 synchronized with the PWM timing 21, the same motor is taken. When the motor current 1 is “positive” and “negative” with respect to the voltage command, a difference occurs in the taken-in motor current 1,
As a result, the control characteristics differ when the motor current 1 is on the “positive” side and the “negative” side.

In addition, current acquisition and current calculation 30
Is performed by interrupt processing at the first position of the PWM timing 21, but after the motor current 1 is taken in,
Calculates the motor voltage command and switches 32 and 33 on both the positive and negative sides.
There is a time delay 40 before the is actually driven.

As described above, in the conventional motor control device, it is unavoidable that there is a time delay from the motor current acquisition to the motor voltage output, and this delay deteriorates the stability of the current control characteristic.

Particularly when a high response motor is adopted,
Since the motor having the same high response has a large current change per unit time, it has a problem that it is difficult to stably control the motor current.

In FIG. 7, 60 is the PWM converter output waveform when the motor voltage command is "positive", 61 is the PWM converter output waveform when the motor voltage command is "negative", and 31 is P
The WM output timing is shown.

The present invention solves the problems in the conventional motor control device described above and eliminates the time delay, thereby controlling the current of the motor, including the case where a high response motor is adopted. An object of the present invention is to provide a motor control device that can be stably operated.

[0015]

The present invention has been made to solve the above-mentioned problems. As a first means thereof, a motor current is fetched into a current calculation section at a constant timing signal to calculate the current. In a motor control device for calculating a motor voltage command and outputting a positive side and a negative side switch drive signal by a switch drive PWM signal obtained by processing the motor voltage command in a PWM converter, the PWM converter is A positive PWM conversion unit and a negative PWM conversion unit are configured in parallel, and a changeover switch that selects and switches the output of the positive PWM conversion unit and the negative PWM conversion unit according to the result signal of the polarity determination of the motor current is provided. A motor control device adapted to obtain the switch driving PWM signal.

That is, according to the first means, with respect to the PWM voltage applied to the motor, the changeover switch is operated to change the application order of the positive side voltage and the negative side voltage according to the polarity of the motor voltage command. The time from applying the voltage to the motor to taking in the motor current can be the same on the positive side and the negative side, and the control characteristics can be the same on the positive side and the negative side.

Further, as a second means of the present invention, in the first means, the timing signal for controlling the intake of the motor current to the current calculation section is supplied through a delay section. The motor control device is provided.

That is, according to the second means, by adjusting the delay between the PWM waveform applied to the motor and the calculation cycle, the time delay from current acquisition to reflection of the calculation result can be shortened. Therefore, the stability of current control can be improved.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a functional block diagram of a motor control device according to this embodiment, and FIG. 2 is a positive PWM.
3 is a functional block diagram of the conversion unit, FIG. 3 is a functional block diagram of the negative PWM conversion unit, and FIG. 4 is an explanatory diagram showing the control timing of the motor control device.

In order to avoid redundant description, the same parts as those of the above-mentioned conventional device are designated by the same reference numerals in the drawings, and the above description is incorporated by reference, and redundant description will be made as much as possible. The items peculiar to the present embodiment will be mainly described by omitting them.

That is, in the present embodiment, in addition to the configuration of the conventional device described above, a motor voltage command 4 is calculated from a current command 2 and a motor current 1 and is followed by a motor voltage command. A positive PWM converter 5a and a negative PWM converter 5b for converting 4 into two PWM signals are provided.

Further, a polarity determination section 50 for determining the polarity of the motor current 1 is provided, and the positive PWM conversion section 5 is based on the polarity determination result signal 51 output from the same polarity determination section 50.
The changeover switch 13 for switching between the two PWM signals from the a and the negative PWM converter 5b is provided.

Further, of the current calculation timing signal 9 and the PWM timing signal 10 generated from the PWM cycle timer 11 which generates the PWM cycle based on the clock signal 12, the timing of the current calculation timing signal 9 is the delay time 15. Delay unit 14 that adjusts based on
Is provided.

In the present embodiment in which the above-mentioned configuration is added to the above-mentioned conventional device, the current command 2,
The motor voltage command 4 to be applied to the motor is calculated by the current calculation unit 3 from the motor current 1 and the motor voltage command 4
Is a positive PW that outputs in the order of "negative" to "positive" side switches.
The M conversion unit 5a and the negative PWM conversion unit 5b that similarly outputs from the "positive" to the "negative" side switches are converted into two PWM signals.

These two PWM signals are selectively switched by the changeover switch 13 in accordance with the polarity determination result signal 51 output from the polarity determination section 50 for determining the polarity of the motor current 1, and become the switch drive PWM signal 6.

The switch drive PWM signal 6 becomes a positive side switch drive signal 7 and a negative side switch drive signal 8 which is inverted by the inverter and is the inverted positive side switch drive signal 7.

As described above, depending on the polarity of the motor current, the ON / OFF order of the positive side switch and the negative side switch is switched, and even if the motor voltage command is positive or negative, the motor current The timing of applying a positive or negative voltage to the motor is the same as the input timing, and as a result, the positive and negative sides of the current control characteristic of the motor are made symmetrical.

The operation and the like of the present embodiment will be described in more detail with some overlap with the above description. In FIG. 1, the current calculator 3 calculates a motor voltage command 4 to be applied to the motor from the current command 2 and the motor current 1 according to the current calculation timing signal 9.

This motor voltage command 4 is converted into a switch driving PWM signal for driving the switch with a duty corresponding to the size of the command value. The "negative" side switch is first, and the "positive" side is later. Positive PWM converter 5a that outputs a pulse that drives a switch, and negative PWM that outputs a pulse that drives a "positive" side switch first and a "negative" side switch later
It is converted into two PWM signals by the converter 5b.

The two PWM signals are output from the polarity determination unit 50, and the polarity determination result signal 51 outputs the positive PWM conversion unit 5a when the motor current 1 is "positive" by the changeover switch 13.
Output, and negative PWM when motor current 1 is "negative"
It is switched to the output of the converter 5b.

As a result of the switching, the switch drive PWM signal 6 output from the changeover switch 13 becomes the positive side switch drive signal 7, and the switch drive PWM signal 6 also outputs the positive side switch drive signal 7 by an inverter. It is inverted and becomes the negative side switch drive signal 8. As a result, when the motor current 1 is "positive", the negative side switch is turned on first, and when the motor current 1 is "negative", the positive side switch is turned on first.

As a result, when the motor current 1 is positive, the positive side switch is turned on later, and conversely, when the motor current 1 is negative, the negative side switch is turned on later. Since the delay becomes smaller with respect to the timing of taking in, the control characteristics of the current flowing through the motor are the same on the positive side and the negative side.

The details of the positive PWM conversion section 5a, the negative PWM conversion section 5b, the delay section 14 and the like in the present embodiment are as follows.

In the negative PWM converter 5b, as shown in FIG. 3, the motor voltage command 4 is converted by the function generator 16 into a count value f (Duty) corresponding to the motor voltage command 4 and stored in the register 18. The output value of the counter 19 that is reset by the PWM timing signal 10 and is up-counted by the clock signal 12 is compared by the comparator 20 to generate the switch drive PWM signal 6 that drives the "negative" side switch to "back".

On the other hand, in the positive PWM converter 5a, the motor voltage command 4 is calculated by the function generator 16 to obtain the output f (Duty) as shown in FIG. The count value held in the register 18 is set as a value subtracted from the above, and this value is compared in the comparator 20 with the output value of the counter 19 similar to the case of the negative PWM converter 5b, and the output of the comparator 20 is compared. By inverting with an inverter, the switch drive PWM signal 6 which drives a "positive" side switch "back" is generated.

Further, the current calculation 30 is operated in synchronization with the PWM timing 21, but the calculation is started before the PWM signal by the time obtained by back-calculating the period required for the calculation, and from the calculation end to the PWM output. Minimize time and control delay.

Since the calculation is periodically performed, the delay unit 14 is interposed between the PWM period timer 11 and the current calculation unit 3 and an appropriate delay (time delay) 28 is inserted from the PWM signal. It can be realized by

The time of this delay (time delay) 28 is set by calculating the delay time from the PWM cycle and the time required for current calculation. Further, since the delay time is affected by the calculation time, it can be easily dealt with without changing the hardware even if the calculation content is changed by making it programmable.

Furthermore, in FIG. 4, 22 is a positive PW.
M conversion output waveform (PWM waveform when motor voltage command is "positive"), 23 is negative PWM conversion output waveform (PWM waveform when motor voltage command is "negative"), 24 is polarity determination result signal output waveform, and 25 is positive side Switch drive signal waveform, 26 is negative side switch drive signal waveform, 27 is current calculation timing, 29
Indicates the current fetch timing, and 31 indicates the PWM output timing.

As described above, according to the present embodiment, the control performance can be improved by minimizing the time delay from the calculation to the PWM output. Further, in the remaining time of the PWM cycle, the calculation in which the control delay is allowed by the current calculation is executed.

Although the present invention has been described above with reference to the illustrated embodiments, the present invention is not limited to such embodiments.
It goes without saying that various modifications may be made to the specific structure within the scope of the present invention.

[0042]

As described above, according to the invention described in claim 1 of the present application, the motor current is fetched into the current calculation unit with a constant timing signal, and the current calculation is performed to calculate the motor voltage command. In a motor control device configured to output a positive side and a negative side switch drive signal according to a switch drive PWM signal obtained by processing a command in a PWM converter, the PWM converter is a positive PWM converter and a negative PWM converter. A changeover switch is provided which is configured in parallel and which selects and switches the outputs of the positive PWM conversion unit and the negative PWM conversion unit according to the result signal of the polarity determination of the motor current, thereby obtaining the switch drive PWM signal. Since the motor controller is configured, the changeover switch is activated to the positive side for the PWM voltage applied to the motor depending on the polarity of the motor voltage command. By changing the order of applying the negative voltage can be the same time from application of voltage to the motor until capture motor current at the positive side and negative side,
It is possible to obtain a suitable motor control device in which the control characteristics can be the same on the positive side and the negative side and the current of the motor can be stably controlled.

According to a second aspect of the present invention, in the first aspect of the invention, the timing signal for controlling the intake of the motor current into the current calculation section is supplied through a delay section. Since the motor control device is configured as described above, by adjusting the delay between the PWM waveform applied to the motor and the calculation cycle, the time delay from current capture to reflection of the calculation result is shortened. Therefore, the stability of the current control is improved, and a suitable motor control device capable of stably controlling the current of the motor can be obtained.

[Brief description of drawings]

FIG. 1 is a functional block diagram of a motor control device according to an embodiment of the present invention.

FIG. 2 is a functional block diagram of a positive PWM conversion unit.

FIG. 3 is a functional block diagram of a negative PWM conversion unit.

FIG. 4 is an explanatory diagram showing a control timing of the motor control device.

FIG. 5 is a control circuit diagram of a half-bridge circuit using a bipolar motor power source of a conventional brush motor.

FIG. 6 is a functional block diagram of a conventional motor control device.

FIG. 7 is an explanatory diagram showing a control timing of a conventional motor control device.

[Explanation of symbols]

1 Motor Current 2 Current Command 3 Current Calculation Unit 4 Motor Voltage Command 5 PWM Converter 5a Positive PWM Converter 5b Negative PWM Converter 6 Switch Drive PWM Signal 7 Positive Switch Drive Signal 8 Negative Switch Drive Signal 9 Current Calculation Timing Signal 10 PWM Timing Signal 11 PWM Cycle Timer 12 Clock Signal 13 Changeover Switch 14 Delay Unit 15 Delay Time 16 Function Generator 17 Subtractor 18 Register 19 Counter 20 Comparator 21 PWM Timing 22 Positive PWM Conversion Output Waveform 23 Negative PWM Conversion Output Waveform 24 Negative polarity determination result signal output waveform 25 Positive side switch drive signal waveform 26 Negative side switch drive signal waveform 27 Current calculation timing 28 Delay 29 Current acquisition timing 30 Current calculation 31 PWM output timing 32 Positive side switch 33 Negative side switch 34 Positive Power supply 35 a negative side power source 36 motor 40 hours behind 50 the polarity judging unit 51 the polarity judgment result signal 60 motor voltage command "positive" when the PWM converter section output waveform 61 motor voltage command "negative" when PWM converter section output waveform

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 5H571 BB06 CC01 EE02 FF09 GG04                       HB01 HD02 JJ03 JJ13 JJ17                       JJ18 LL22

Claims (2)

[Claims] 1. A switch driving PWM signal obtained by fetching a motor current into a current calculation unit with a constant timing signal, performing a current calculation to calculate a motor voltage command, and processing the motor voltage command in a PWM conversion unit. In a motor control device configured to output a positive side and a negative side switch drive signal, the PWM conversion unit is configured in parallel with a positive PWM conversion unit and a negative PWM conversion unit, and a result signal of the polarity determination of the motor current is performed. A motor control device comprising a changeover switch for selecting and switching between outputs of the positive PWM conversion unit and the negative PWM conversion unit, and thereby obtaining the switch drive PWM signal. 2. The timing signal for controlling the intake of the motor current to the current calculation unit is supplied through a delay unit.
The motor control device according to.