JPS6264289A - Rotor position detecting method for brushless dc motor - Google Patents

Abstract

PURPOSE:To drive a motor efficiently with high load torque at a high speed by holding an induced voltage containing a commutation spike for the prescribed time duration to set a signal for driving the motor. CONSTITUTION:An induced voltage from the neutral point N of an armature winding by driving a motor 2 is divided by resistors R1, R2, and applied to a gate circuit 4. When a gate signal set in advance equal to the maximum commutation spike continuing time within load condition used for the motor 2 synchronously with the commutation spike or to corresponding time duration is applied from a gate signal generator 5, an induced voltage signal is applied through a gate circuit 4 and an impedance converter of a capacitor C1 and an operational amplifier OP1 to become a sample holding signal to a controller 3. The controller 3 controls a semiconductor commutator 1.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention provides a brushless direct current motor (hereinafter abbreviated as a motor) having a magnet rotor, in which the induced voltage generated in the armature winding due to the rotation of the magnet rotor is reduced. The present invention relates to a method for detecting the position of a magnet rotor from an induced voltage in a control device that uses the magnet rotor to drive the magnet.

[Conventional technology]

Conventionally, the magnetic rotor position detection means of the control device that drives this type of motor, which uses a magnetic detection means such as a Hall element inside the motor, has problems with structural and manufacturing complexity and heat resistance. In order to solve these problems, many methods have been proposed that utilize the induced voltage generated in the armature winding in a non-energized state due to the rotation of the magnet rotor of the motor.

One of them is to obtain the induced voltage from the neutral point of the star-connected three-phase armature windings of the motor, and to obtain the amplitude change signal of the induced voltage after delaying the phase by 90 degrees in electrical angle. A method has been proposed in which the position detection signal phase is obtained by comparing at the center of the signal.

An example thereof is shown and explained in FIG. 8. FIGS. 9 and 10 are timing charts showing waveforms of each part in FIG. 8.

1 is a semiconductor commutator device, which includes energization control elements 18 to 1;
r connected to a three-phase bridge.

A DI-Da flywheel diode is connected in antiparallel to each energization control element. Reference numeral 2 indicates a motor, and reference numeral 3 indicates a control circuit.

Now, each energization control element of the semiconductor commutator 1 is sequentially activated by the electrical angle 12 by the drive signal shown by Va-Ve in FIG.
If the motor 2 is controlled to be energized at 0° and cut off at 240°, then the armature windings Lu, L of the motor 2 are de-energized by the rotation of the magnet rotor of the motor 2.
An induced voltage is sequentially generated in each of v and Lw.

Therefore, at the neutral point of the armature windings Lu, Lv, Lw, the voltage V supplied to the semiconductor commutator 1,
The induced voltage appears around the voltage at .

The induced voltage is divided by resistors IL and R2 to obtain an induced voltage signal V.

get.

The induced voltage signal ■. A shift signal 'V/ is obtained by delaying the phase by 90° with respect to the amplitude by capacitor integration, and by comparing and logicing the shift signal VS at the center of the amplitude, a logic position detection signal v0 is obtained.

The rising and falling timings of the logical position detection signal V, as shown in FIG. If the detection signal v9 is energized, drive signals Va to vf necessary for continuously rotating the motor 2 can be obtained, and as a result, the motor 2 is feedback-controlled.

[Problem that the invention seeks to solve]

However, the case where the motor can be operated by the above signal processing is when the load applied to the motor 2 is light, and when the load is heavy and the current flowing to the motor 2 increases, the energization control in the semiconductor commutator device l Four commutation spikes occur each time an element is turned off, and a normal logical position detection signal v0 cannot be obtained.

For example, the energization command state of the drive signals Va and vr (here,
Power is supplied from the semiconductor unit 1 to the motor 2 through an energization control element] a - Armature winding L to neutral point N-+1π
This is done through a path from the machine winding Lw to the energization control element 1f.

Next, when the energization pattern of the semiconductor commutator device 1 changes, the energization control element 1a is cut off, and the energization control element 1a is switched off.
b becomes energized.

Therefore, the energization pattern at this time is the energization control element 1h-
・The path is armature winding Lv→neutral point N−armature winding Lw+energization control element 1f.

However, the armature winding Lu, which was in the energized state immediately before the energization pattern changed, generates a back electromotive force, generally called a commutation spike, in order to release the inductance energy stored by the energization after the energization is cut off. , armature winding Lu→neutral point N→armature winding L and electric control element 1→7
A closed circuit is formed from the lie wheel diode D4 to the armature winding Lu to flow a return current.

In this example, the energization control elements of the upper arm of the semiconductor commutator device 1 are cut off, but if the lower arm is cut off, for example, the energization can be controlled from the energized state of the energization control elements 1b and 1''. In the case of the energization pattern of elements 1b and 1d, armature winding LW force ≦ energization is cut off, so an electromotive force is generated in armature windings I and svj, and armature winding LW-17 line Wheel diode D3 → energization control element 1b - armature winding Lv → neutral point - armature winding LW
Inductance energy is released by passing a return current through the closed circuit.

Similarly, in other energization patterns, a commutation spike occurs at the moment when the conduction of the energization control element is interrupted until the inductance energy of the armature winding whose energization is interrupted is released.

In the above situation, normally the armature winding with current cut off would not generate induced voltage due to the rotation of the m5 rotor, but when the armature winding is energized like this, the induced voltage is stored. A commutation spike is generated to release the energy, and the back electromotive force of the commutation spike appears at the neutral point.

This commutation spike disappears once the stored energy is released from the armature winding, but the longer the stored energy is, i.e. the greater the current flowing through the armature winding, the longer it will last. .

Now, assuming that each armature winding has an inductance of Lx, the energy Wt stored in the armature winding of each phase is W[,=="Lxi'...
...Equation 1 (the plate is the current flowing through the armature winding), and increases in proportion to the square of the current flowing through the armature winding.

Further, in this type of motor, the current flowing through the armature is approximately proportional to the load 1-lux applied to the motor.

Therefore, as the load torque of the motor 2 increases, the width of the commutation spike increases as shown in the induced voltage signal V8 in FIG. 10, and as a result, the area where the induced voltage is generated becomes narrower.

The induced voltage signal V is in this state. When capacitor integration is performed for a 90° phase shift, the shift signal V/ is affected by the commutation spike near the center of the amplitude as shown in Figure 10, yS, and the slope of the signal changes from the originally required shift 1 to the slope of the signal. A waveform with a slope in the opposite direction appears. Therefore, even if an attempt is made to obtain a logical position detection signal by converging such a waveform at the center of the amplitude, the waveform will be distorted as shown in the logical position detection signal V,1 in FIG.
control becomes impossible.

Also, suppose that the shift signal V/ in FIG. 10 is used to shift motor 2.
In order to drive the shift signal V/, it is necessary to apply a large hysteresis when comparing the shift signal V/.

For example, the hysteresis level VHH to VI shown in FIG.
Set the IL and set the hysteresis level VIIH to logic H.
Hysteresis level VHL to IGH level is logic L
If the change point level is set to the OW level, it is possible to send out the drive signals Va-Vf for driving the motor 2 in the regular order, but the Δ time period 7 shown in FIG.
The logical position detection signal does not start until the time when the signal yS passes through the center of its amplitude.

As a result, the motor 2 is inevitably driven in a phase that lags with respect to the correct position of the magnet rotor, resulting in poor efficiency of the motor 2.

Furthermore, if the motor 2 is to be rotated at high speed, the frequency of the induced voltage signal V increases and the amplitude period becomes short.

However, the duration of the commutation spike is unrelated to the frequency of the induced voltage signal V8 as described above, and is almost determined by the load torque l of the motor 2, so if the load torque is the same, the high speed The more it is, the narrower the range of induced voltage becomes.

As described above, the conventional method of obtaining a shift signal with a 90° phase delay by integrating an induced voltage signal with a capacitor cannot efficiently drive a motor at high load torque and high speed.

[Means to solve the problem]

The present invention has been made in view of the above, and commutation spikes occur starting from the moment when the energization pattern in the power supply to the armature windings of the motor is switched, and the duration thereof is determined by the position of the motor rotor. If the energization timing is constant, the energization control element of the semiconductor commutator device is controlled by focusing on the point that it is proportional to the load torque applied to the motor.
Starting from the rise or fall of the six drive signals or the logic position detection signal that changes without phase difference with the six drive signals, the time period is set in advance to be equal to or equivalent to the maximum duration of the commutation spike. The motor is configured to send out a gate signal, and the gate signal holds an induced voltage signal containing commutation spikes obtained from the armature winding of the motor, thereby removing the commutation spikes.

〔Example〕

FIG. 1 shows a configuration diagram of the present invention, and FIG. 2F and waveforms of various parts in FIG.

In Fig. 1 f, 4 is a gate circuit, 5 is a gate signal generation circuit, v2 is an induced voltage signal, vo is a data l- signal,
, are sample-and-hold signals, and in FIG. 2, v; is a shift signal obtained by delaying the sample-and-hold signal by 90° in phase by condenser integration in the control circuit 3, and V;

\ is V; similarly, it is a logical position detection signal obtained by comparing the shift signal v/ at the center of the amplitude within the control circuit 3.

Induced voltage signal V. is sent to the control circuit 3 as a sample and hold signal V via the gelt circuit 4, and the gate circuit 4
is controlled by the gate signal v6 sent from the gate signal generation circuit 5 to hold the induced voltage signal v, .

If the motor 2 is currently being driven, an induced voltage signal Vi is obtained from the neutral point N of the armature winding of the motor 2, which is divided by the resistors R, , R2.

The induced voltage signal V. is a signal containing commutation spikes as shown in Figure @2.

Here, a gate signal v0 is synchronized with the commutation spike and is set in advance to a time width equal to or equivalent to the maximum commutation spike duration within the load conditions used by the motor 2.
When data 1 is sent out from the signal generating circuit 5, the induced voltage signal V is held for the time of the gate signal v6 through impedance conversion by the gate circuit 4, capacitor C3, and operational amplifier OP, and the other The time signal becomes a sample-and-hold signal (2) and is sent to the control circuit 3 by a sample-and-hold operation in which the induced voltage signal Va passes.

Here, the capacitor C1 is carried out via the gate circuit 4.
If the charging/discharging time is sufficiently small compared to the period f of the induced voltage signal, it is possible to obtain a sample hold signal V that follows the induced voltage signal vw with almost no phase difference.

The sample-and-hold signal V is a signal that does not include commutation spikes, as shown in the waveform shown in FIG.

This is because, if the maximum duration of a commutation spike is Tww, the hold command time T for the gate signal V set to hold the induced voltage signal V for the gate circuit 4 is given by T = T, ...Equation 2 Iζ is preset (this is because the gate signal V0 is sent out in synchronization with the occurrence of the commutation spike).

Therefore, the sample hold signal processed in this way■,
If so, even if conode nosa integration is performed in the control circuit 3, a shift signal V having an approximately triangular wave amplitude delayed by 90 degrees in phase with respect to the sample and hold signal V, i can be obtained, and the conventional example When such an induced voltage signal V is directly integrated using a conotensor, no waveform disturbance occurs near the center of the amplitude.

Therefore, when comparing the sample and hold signal V at the center of the amplitude to obtain the logical position detection signal V, there is no need to add hysteresis or tellence, and as a result, the rotation of the magnet rotor of the motor 2 In contrast, a normal logical position detection signal v0 can be obtained.

FIG. 3 is a configuration diagram showing another embodiment of the present invention, in which three-phase house-connected resistors Ru, Rv, l'bv of equal values are connected to the output terminal of the semiconductor commutator device l, and the induced voltage signal V . The signal source is determined at the star-shaped connection point N' of the resistor, and everyone knows that the star-shaped connection point N' of the resistor is the virtual neutral point of the motor 2.

Therefore, the neutral point N of the motor 2 and the star-shaped connection point N' of the resistor are completely equivalent, and the present invention can be applied as in the case of FIGS. 1 and 2 described above.

Now, the gate signal v0 in the present invention is an important element and must be output without a phase difference from the commutation spike.

However, this can be easily achieved.

This is because commutation spikes occur from the moment the energization pattern of the semiconductor commutator device is switched, so the drive signal Cζ that drives the energization control element of the semiconductor commutator device is completely synchronized, and the drive signal is In a control device to which the present invention is applied, which utilizes the induced voltage at the neutral point of the armature winding, the logical position detection signal f is synchronized.

Therefore, by transmitting a signal for a certain period of time in synchronization with the rise and fall of these signals, the gate signal necessary for the present invention can be obtained.

FIG. 4 shows a first embodiment of the gate signal generation circuit, and FIG. 5 shows a timing chart of signal waveforms of various parts related to FIG. 4.

5u to 5w and 5x to 5z are rising edge detection circuits, B1 is a waveform shaping circuit, and P is a NOR circuit.

The rising edge of each drive signal output from the control circuit 3 to the semiconductor fumutator device 1 is set to a logic high level for a time determined by the shaping level of the capacitor C2 and the waveform shaping circuit B.
H level signals tu, tv, tw, Lx
.

Obtain each edge pulse signal of ty; tz.

By NORing each of the edge pulse signals, the gate signal V according to the present invention shown in FIG. 1 can be obtained over a wide range of settings by changing the waveform shaping level.

Also, in the explanation, the case of a rising edge was explained, but as is clear from comparing each drive signal in FIG. 5, for example, the rise of the drive signal U coincides with the fall of the drive signal W. In other words, the rising edge of each drive signal is also the falling edge of the other driving signal.

Therefore, it is possible to obtain an edge pulse signal at the falling edge of each drive signal, or by appropriately combining rising and falling edge pulse signals.

The second embodiment of the gate signal generation circuit is shown in the following f and Fig. 6, and the waveforms of the signals at each part in Fig. 71ζ are shown in timing charts, and will be explained below with reference to both figures. .

In the case of the embodiment of the water bottle 2, both the rising and falling edges of the logical position detection signal V obtained as a result of the application of the present invention described in FIG. 1 are detected.

Logicized position detection signal VL, which is a part of the control circuit 3 in the figure.
This shows the circuit used to obtain .

E1. tExclusive OR circuit is shown, F
is an inverting circuit.

Originally, the control device to which the present invention is applied is configured to process an induced voltage signal whose signal source is the neutral point of the armature winding of the motor, as explained in FIGS. 8 and 9. There is.

Therefore, since the induced voltage signal is single, the induced voltage signal must contain all the information necessary to obtain the drive signal to the semiconductor commutator.

In fact, as explained in FIGS. 8 and 9 of the conventional example, the drive signal is sent out in synchronization with the rise and fall of the logical position detection signal, and as a result, the motor can continue to rotate.

In this case, six drive signals are obtained from one logical position detection signal f, so a change in the logical position detection signal is a change in the energization pattern of the semiconductor commutator device. This is also the origin of commutation spikes.

From the above, as shown in FIG. 6, the logical position detection signal V is input to one input terminal Cζ of the mismatch circuit E without a phase difference, and the logical position detection signal v is input to the other input terminal Cζ. The phase is delayed by integration using the capacitor C3 and the resistor, and then inverted by the inverting circuit F. In other words, the logical position detection signals v are determined by the time constants of the capacitor C3 and resistor R3, and the input threshold level of the inverting circuit F. When inputting the inverted delayed phase signal V, which has been delayed and inverted by the time to Since the levels match, the gate signal v0 shown in FIG. 7 becomes the logical position detection signal v
It is obtained as a signal that changes to a logic LOW level starting from the rising and falling edges of 0.

The configuration of the present invention shown in FIG. 1 can be achieved if the gate circuit for the gate signals V and jζ is controlled to be at a logic LOW level and to prevent the induced voltage signal vw from passing through.

〔Effect of the invention〕

As explained above, according to the present invention, in the control method for driving this type of motor using the induced voltage generated at the neutral point of the armature winding of the motor due to the rotation lζ of the motor, the commutation The occurrence of a spike is detected without a phase difference, and a commutation spike is detected in advance from the origin of the commutation spike with a time width equal to or close to the duration width of the maximum commutation spike within the motor operating range. Since the induced voltage signal contained therein is held, the commutation spike component contained in the induced voltage signal is prevented from passing through the holding means and beyond.

In the present invention, since the sample hold signal obtained in this way is used as a signal for driving the motor, the first
As shown in figure O, due to the influence of commutation spikes, the waveform around the center of the amplitude of the shift signal is not disturbed when a 90° delayed phase shift is performed by capacitor integration.

Therefore, by comparing the shift signals at the center of their amplitudes, it is no longer necessary to provide hysteresis in consideration of the influence of commutation spikes when obtaining the logical position detection signal Cζ. It is possible to obtain a logical position detection signal with a phase state necessary for driving.

Therefore, the motor can be operated efficiently even if it is operated at high speed, low speed, high torque, low torque, or a combination thereof.

Furthermore, the gate signal necessary for sampling and holding the induced voltage signal can also be obtained within the circuit range supplied with the control power supply voltage, as shown in the embodiment of the gate signal generation circuit shown in FIGS. 4 and 6 fζ. Therefore, there is no need to detect the actual commutation spike itself, and problems such as the magnitude of the voltage of the commutation spike itself and the potential with respect to the control power supply voltage can be ignored.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention. FIG. 2 is a timing chart showing waveforms of signals at various parts in FIG. 1 and signals illustrated for explaining FIG. 1. FIG. 3 is a configuration diagram showing another embodiment of the present invention. FIG. 4 is a block diagram showing the first embodiment of the gate signal generation circuit, and FIG. 5 is a timing chart showing the waveforms of each signal in the diagram of FIG. FIG. 6 is a circuit configuration diagram showing a second embodiment of the gate signal generation circuit. FIG. 7 is a timing chart showing the waveforms of each signal in the diagram of FIG. 6; FIG. 8 is a configuration diagram showing a conventional example. FIGS. 9 and 10 are tie-2 diagrams showing waveforms of signals at various parts in FIG. 8 and waveforms of processed signals for explaining FIG. 1...Semiconductor commutator device 2...Brushless DC motor 3...Control circuit 4...Gate circuit 5 -Gate signal generation circuit OF,...Operation amplifier circuit 5U~5W・5X~5Z...Rising edge detection circuit B1...Waveform shaping circuit D...NOR circuit E...-E+xclusive OR circuit I?・・・
・Inversion circuit Figure 1 Figure 2 ＼b Figure 4 Figure 5" 5rilJ Figure 6 Figure 7 Figure 8

Claims (1)

[Claims] 1. A brushless DC motor having a magnetic rotor, a star-connected armature winding, and a semiconductor commutator device comprising six energization control elements connected to a three-phase bridge, as described above. In a control method that uses an induced voltage signal obtained from the neutral point of the armature winding or a virtual neutral point equivalent to the neutral point to drive the armature winding, the transition that occurs when the energization control element is energized is A method for detecting a rotor position of a brushless DC motor, characterized in that the induced voltage signal is held in synchronization with a commutation spike for a maximum duration of the commutation spike or a time close to the maximum duration of the commutation spike. 2. The rotor of the brushless DC motor according to claim 1, wherein the timing for holding the induced voltage signal is set at the rising edge or falling edge of the drive signal of the energization control element, or a mixture of both. Location detection method. 3. The timing for holding the induced voltage signal is based on the rise and fall of the logical position detection signal obtained by converting the induced voltage signal into a shift signal whose phase is delayed by 90° and comparing the shifted signal at the center of the amplitude. 2. A method for detecting a rotor position of a brushless DC motor according to claim 1, wherein the starting point is .