JP3084496B2 - Control device for synchronous motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voltage-type PWM inverter capable of changing the speed of a synchronous motor, and more particularly to a digitally controlled transistor, MOSFET, IGBT (Insu).
lateted bipolar transmission
The present invention relates to a synchronous motor control device suitable for controlling an inverter using a high-speed switching element (tor).

[0002]

2. Description of the Related Art Conventionally, in an inverter device for controlling a synchronous motor at a variable speed, an upper and lower arm which constitutes a main circuit of the inverter does not have a short circuit in terms of switching timing.
The output current of the inverter is distorted by the effect of the provided dead time. As a result, the motor current is also distorted, the torque pulsation increases, and the motor efficiency decreases.

[0003] Further, in the conventional inverter device, as a means for correcting the dead time, an AC current regulator for detecting the input current of the motor and controlling the detected value to match the command value is provided.

On the other hand, regarding dead time correction in an induction motor, the voltage of a switching element of an inverter is measured, and a narrow pulse narrower than a reference PWM pulse width by a fixed correction amount Tλ in accordance with the polarity of the error voltage is fixed. By switching a wide pulse that is wide by the amount Tλ, the second PWM
A method of correcting a dead time as a signal (input signal of a dead time circuit) has been proposed (JP-A-2-46963).

[0005]

In the above prior art, the provision of a current controller is firstly required to realize high-speed processing when implementing an inverter by digital control.
High-speed microcomputers and peripherals are needed,
There was a problem that the device became complicated.

On the other hand, when the conventional dead time correction method in an induction motor is to be applied to a synchronous motor as it is, there is a problem that a detector for voltage, current and the like is required, and the device becomes complicated.

In the present invention, the speed control (ASR) and the current control (ACR) of a synchronous motor having a built-in permanent magnet are all digitally controlled on the dq axes obtained by three-phase / two-phase conversion in so-called vector control. Then, according to the polarity of the phase current of the synchronous motor, a narrow pulse narrower than the reference PWM pulse width by the correction amount Tλ and a wide pulse wider by the correction amount Tλ are switched to operate at optimum torque and optimum efficiency. Is what you do.

Here, since the magnetic flux of the synchronous motor is established in the permanent magnet or the field winding, the d-axis command is always zero. The q-axis current can determine whether the torque is positive or negative, but since it is a DC component, it cannot determine the polarity of the phase current of the synchronous motor.

A first object of the present invention is to provide a synchronous motor control method and apparatus capable of easily performing dead time correction in a synchronous motor.

Further, when the load condition becomes close to no load, the q-axis current becomes small, and it may be difficult to determine the polarity of the q-axis current due to addition of noise and the like and vibration of the control system. For example, a negative polarity is detected in spite of a positive polarity of the current, so that the dead time cannot be accurately corrected, torque pulsation may increase, or motor efficiency may decrease.

A second object of the present invention is to provide a synchronous motor control method and apparatus which can perform dead time correction in a synchronous motor with high accuracy.

It is a third object of the present invention to provide a synchronous motor control method and apparatus capable of performing dead time correction which is important for high-speed response in a synchronous motor.

[0013]

According to the present invention, there is provided a synchronous motor control method comprising the steps of: delaying the PWM signal supplied to a PWM inverter that outputs a variable voltage at a variable frequency based on the PWM signal for driving the synchronous motor; In a synchronous motor control method for correcting a dead time set by a dead time setting circuit to prevent an arm short circuit of a switching element constituting a main circuit of the PWM inverter, a detection value of a rotation of a rotor in the synchronous motor and A current polarity of a phase current of the synchronous motor is obtained based on a torque current command value determined based on a rotation speed command of the synchronous motor and a detected magnetic pole position of a rotor in the synchronous motor, and the PWM signal is obtained. Set by the dead time setting circuit based on the current polarity of the phase current of the synchronous motor. And performing correction of Ttotaimu.

According to the synchronous motor control method of the present invention, the PWM is supplied to a PWM inverter which outputs a variable voltage at a variable frequency based on a PWM signal for driving the synchronous motor.
In a synchronous motor control method for correcting a dead time set by a dead time setting circuit for delaying a signal to prevent an arm short-circuit of a switching element forming a main circuit of the PWM inverter, the rotation of the synchronous motor A current polarity of a phase current of the synchronous motor is obtained based on a speed command value and a detected magnetic pole position of a rotor in the synchronous motor, and the dead current is determined based on the PWM signal and a current polarity of the obtained phase current of the synchronous motor. The dead time set by the time setting circuit is corrected.

According to the method of controlling a synchronous motor of the present invention, the PWM is supplied to a PWM inverter which outputs a variable voltage at a variable frequency based on a PWM signal for driving the synchronous motor.
In a synchronous motor control method for correcting a dead time set by a dead time setting circuit to delay a signal and prevent an arm short-circuit of a switching element forming a main circuit of the PWM inverter, the rotation of the synchronous motor When it is determined that the torque current command value determined based on the rotation detection value of the rotor and the rotation speed command of the synchronous motor is large, based on the torque current command value and the magnetic pole position detection value of the rotor in the synchronous motor. The current polarity of the phase current of the synchronous motor is obtained, and when it is determined that the torque current command value is small, the phase current of the synchronous motor is determined based on the rotational speed command value of the synchronous motor and the magnetic pole position detection value. A current polarity is determined, and the dead time setting cycle is determined based on the PWM signal and the determined current polarity of the phase current of the synchronous motor. And performing correction of the dead time set by.

A control device for a synchronous motor according to the present invention is a control device for a PWM inverter that outputs a variable voltage at a variable frequency based on a PWM signal for driving the synchronous motor,
In a synchronous motor control device having a dead time setting circuit for delaying the PWM signal and preventing an arm short-circuit of a switching element constituting a main circuit of the PWM inverter, a magnetic pole position of a rotor in the synchronous motor is determined. Magnetic pole position detection means for detecting, rotation speed detection means for detecting the rotation speed of the rotor in the synchronous motor, rotation speed command means for commanding the rotation speed of the synchronous motor, the rotation detection value and the rotation speed command Speed control means for outputting a torque current command based on the torque current command value and the magnetic pole position detection value, current polarity determination means for obtaining the current polarity of the phase current of the synchronous motor, and the PWM signal and the PWM signal. The dead time based on a signal indicating the current polarity of the phase current of the synchronous motor output from the current polarity determination means. And having a dead time correcting means for correcting the dead time set by the constant circuit.

A control device for a synchronous motor according to the present invention is a control device for a PWM inverter that outputs a variable voltage at a variable frequency based on a PWM signal for driving the synchronous motor,
In a synchronous motor control device having a dead time setting circuit for delaying the PWM signal and preventing an arm short-circuit of a switching element constituting a main circuit of the PWM inverter, a magnetic pole position of a rotor in the synchronous motor is determined. Magnetic pole position detection means for detecting, rotation speed detection means for detecting the rotation speed of the rotor in the synchronous motor, rotation speed command means for commanding the rotation speed of the synchronous motor, the rotation detection value and the rotation speed command Speed control means for outputting a torque current command based on the current speed and current polarity determination means for determining the current polarity of the phase current of the synchronous motor based on the rotational speed command value and the magnetic pole position detection value,
Dead time correction means for correcting the dead time set by the dead time setting circuit based on the PWM signal and a signal indicating the current polarity of the phase current of the synchronous motor output from the current polarity determination means. It is characterized by the following.

The control device for a synchronous motor according to the present invention is a control device for a PWM inverter that outputs a variable voltage at a variable frequency based on a PWM signal for driving the synchronous motor,
In a synchronous motor control device having a dead time setting circuit for delaying the PWM signal and preventing an arm short-circuit of a switching element constituting a main circuit of the PWM inverter, a magnetic pole position of a rotor in the synchronous motor is determined. Magnetic pole position detection means for detecting, rotation speed detection means for detecting the rotation speed of the rotor in the synchronous motor, rotation speed command means for commanding the rotation speed of the synchronous motor, the rotation detection value and the rotation speed command Speed control means for outputting a torque current command based on the torque current command value determining means for determining the magnitude of the torque current command value; and determining that the torque current command value is large by the torque current command value determining means. Is performed, the current pole of the phase current of the synchronous motor is determined based on the torque current command value and the magnetic pole position detection value. Current polarity determining means for determining the current polarity of the phase current of the synchronous motor based on the rotational speed command value and the magnetic pole position detection value when it is determined that the torque current command value is small; and And a dead time correcting means for correcting a dead time set by the dead time setting circuit based on a signal indicating a current polarity of a phase current of the synchronous motor output from the current polarity determining means. .

That is, in order to achieve the first object, the present invention provides a three-phase square wave signal UM indicating the respective magnetic pole positions of a synchronous motor having the same phase as the induced voltage directly connected to the synchronous motor and having a phase difference of 120 degrees from each other. In the magnetic pole detector that outputs VM, WM, the phase current of the synchronous motor is determined based on the polarity of the signal obtained by multiplying the three-phase square wave signals UM, VM, WM and the sign of the q-axis current command. The dead time is corrected by determining the polarity.

According to the present invention, in order to achieve the second object, a synchronous motor is directly connected to a rotational speed detector, and a rotational speed feedback signal Nf detected from the rotational speed detector is provided.
Alternatively, the dead time is corrected by determining the polarity of the phase current of the synchronous motor based on the polarity of a signal obtained by multiplying the sign of the rotation speed command N by the detection output of the magnetic pole detector. Things.

Further, in order to achieve the third object, the present invention determines the magnitude of a q-axis current command or a detected value of a q-axis current, and when the magnitude is larger than a prescribed value, the value of the magnetic detector is determined. Phase square wave signals UM, VM, WM and q-axis current command or q
The dead time is corrected by determining the polarity of the phase current of the synchronous motor based on the polarity of the signal obtained by multiplying the sign of the shaft current detection value, and correcting the q-axis current command or q
When the magnitude of the shaft current detection value is smaller than the specified value, the detection output of the magnetic pole detector is multiplied by the rotation speed command N or the sign of the detected rotation speed feedback signal Nf based on the polarity of the signal obtained. The dead time is corrected by determining the polarity of the phase current of the synchronous motor.

[0022]

The principle of correcting the dead time according to the present invention is as follows.
In a PWM inverter having a switching element having a feedback diode connected in anti-parallel in the upper and lower arms of the main circuit, when the load current is positive, the load current is continuous while both of the switching elements forming the upper and lower arms are off. Try to flow. In this case, in order for the load current to flow continuously, the load current flows through the feedback diode of the lower arm. As a result, the time during which the motor terminal is fixed to the negative power source becomes longer, and a current smaller than the actual current flows.

When the load current is negative and the switching elements forming the upper and lower arms are both off, the load current tends to flow continuously. In this case, the load current flows through the feedback diode of the upper arm. As a result, the time during which the motor terminal is fixed to the positive power supply becomes longer, and a current larger than the actual current flows.

Therefore, in the present invention, considering the state when the torque command (q-axis command) is positive, the magnetic pole position signal is set so that the phase is the same as that of the induced voltage. The output of the detector will simulate the motor current. When the load current is positive, the magnetic pole position signal simulating the sign of the load current is positive. Therefore, the sign of the actual load current can be detected as positive by multiplying the sign of the torque command by the magnetic pole position signal. Therefore, the reference P
A wide pulse that is wider than the WM pulse width by the correction amount Tλ is switched and used as a second PWM signal (input signal to the dead time circuit).

When the sign of the load current is negative, the magnetic pole position signal simulating the sign of the load current is negative. By multiplying the sign of the torque command by the magnetic pole position signal, a negative sign of the actual load current can be detected. Therefore, the reference PWM
The pulse width is switched to a narrow pulse narrower than the pulse width by the correction amount Tλ to be a second PWM signal (input signal of the dead time circuit).

Considering the state when the torque command (q-axis command) is negative, when the magnetic pole position signal simulating the sign of the load current is positive, the sign of the torque command is multiplied by the magnetic pole position signal to obtain a negative value. Therefore, the state becomes the same as when the load current is negative, and a negative torque is generated. Therefore, the reference PWM
The pulse width is switched to a narrow pulse narrower than the pulse width by the correction amount Tλ to be a second PWM signal (input signal of the dead time circuit). Further, when the magnetic pole position signal simulating the sign of the load current is negative, multiplying the sign of the torque command by the magnetic pole position signal results in a positive value, so that the state is the same as when the load current is positive. For this reason, a wide pulse that is wider than the reference PWM pulse width by the correction amount Tλ is switched to be the second PWM signal (input signal to the dead time circuit).

Thus, current distortion is reduced and torque pulsation is reduced.

In the present invention, since the polarity current of the synchronous motor is determined based on the polarity of the rotation speed command or the speed detection signal and the magnetic pole position detection signal, which are less affected by noise, the state approaches a no-load state and the q-axis current is reduced. The dead time can be corrected with high accuracy even if the value of becomes small.

As described above, according to the present invention, the use of the magnetic pole position detection signal used for speed control of the synchronous motor eliminates the need for a special and compensation detection circuit.

Further, in the present invention, q
Depending on the magnitude of the axis current, when the q-axis current is large, the sign of the q-axis current or the q-axis current command is multiplied by the magnetic pole position signal to simulate the sign of the actual load current, and when the q-axis current is small, the rotation is performed. By multiplying the sign of the speed command or the rotation speed feedback signal by the magnetic pole position signal to simulate the sign of the actual load current, the dead time correction method can be switched even for load fluctuations to achieve high speed. Can respond.

[0031]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a control device of a voltage-type PWM inverter for controlling a synchronous motor to which the present invention is applied. FIGS. 2 and 3 show the operation principle of the control device of a synchronous motor according to the present invention. It is a time chart shown.

In FIG. 1, reference numeral 1 denotes a synchronous motor having a permanent magnet in a rotor, and reference numeral 2 denotes a magnetic pole position detector for detecting an induced voltage of the synchronous motor 1.

Reference numeral 3 denotes a rotation detector such as an encoder for detecting the number of rotations of the synchronous motor 1, and reference numerals 4 and 5 denote current detectors for detecting a motor current of the synchronous motor 1.

Reference numeral 6 denotes an inverter for supplying AC power of an arbitrary frequency to the synchronous motor 1;
Is a rectifier that converts AC power of the commercial power supply 7 to DC power and supplies DC power to the inverter 6.

Reference numeral 9 denotes an A / D converter for converting an analog motor current detected from the current detectors 4 and 5 at predetermined time intervals into a digital signal, and 10 denotes a synchronous motor current IU, IV converted into a digital signal. , IW to the q-axis current Iq
This is a three-phase / two-phase conversion circuit that converts the current into f-axis and d-axis currents Idf. The three-phase / two-phase conversion is performed based on the following equations (1) and (2).

[0036]

(Equation 1)

[0037]

(Equation 2)

As shown in FIG. 2, the magnetic pole position detecting circuit 11
Are induced voltages eou, eov, eo in the synchronous motor 1.
The three-phase square waves UM, VM, and WM are output based on the output from the magnetic pole position detector 2 so as to match the phase of w. 12 is a sin θ / cos θ table.

Further, the magnetic pole position detecting circuit 11 is obtained by the above equation (2)
The signal from the rotation detector 3 is fetched in order to satisfy the following condition, and the electrical angle θ of the rotor of the synchronous motor 1 is accurately detected. Then, the data of the sin θ / cos θ table 12 is accurately obtained.

On the other hand, reference numeral 13 denotes a speed detection circuit, which measures a signal pulse from the rotation detector 3 at regular time intervals and sets it as PN, as well as the first pulse of a constant time (sampling time) and the first pulse after the end of the constant time. Is measured, and the rotation speed feedback signal Nf is obtained using the following equation (3) as the time width TD.

[0041]

(Equation 3)

Here, KN is a conversion coefficient.

Reference numerals 14, 15, and 16 denote adders.
7 is a speed control arithmetic circuit, 18 is a q-axis current control arithmetic circuit,
19 is a d-axis current control operation circuit.

The adder 14 calculates the deviation between the rotation speed command N and the rotation speed feedback signal Nf, and the speed control calculation circuit 17 performs a proportional / integral calculation to output a q-axis current command IQ. The adder 15 calculates the deviation between the q-axis current command IQ and the q-axis current feedback signal Iqf, and the q-axis current control calculation circuit 18 performs a proportional / integral calculation to perform the q-axis voltage command V
Output Q.

The adder 16 calculates a deviation between the d-axis current command ID and the d-axis current feedback signal Idf, and the d-axis current control calculation circuit 19 performs a proportional / integral calculation to output a d-axis voltage command VD. Reference numeral 20 denotes a vector operation circuit, and reference numeral 21 denotes a PWM pulse generation circuit. The vector calculation calculates the absolute value Vtu of the voltage from the q-axis voltage command VQ and the d-axis voltage command VD based on the following equation (4), and calculates the electrical angle θ of the rotor of the synchronous motor 1 obtained from the magnetic pole position detection circuit 11. Based on the following equation (5), a phase γ to be generated is calculated from the following equation (5), and a PWM pulse of a vector corresponding to the U phase voltage Vtu and the phase γ is output from the PWM generation circuit 21 to the U, V, W phase signals, S1U,
S1V and S1W are output.

[0046]

(Equation 4)

[0047]

(Equation 5)

[0048]

(Equation 6)

Reference numeral 22 denotes a polarity discrimination switching circuit.
3 is a dead time correction circuit, and 24 is a dead time circuit.

The polarity discrimination switching circuit 22 fetches the magnetic pole position signals UM, VM, WM from the magnetic pole position detecting circuit 11, and further outputs a q-axis current command IQ which is an output of the speed control operation circuit 17.
Then, the rotation speed command N is fetched. The polarity discrimination switching circuit 22 outputs the output signals UM, VM, W of the magnetic pole position detection circuit 11.
The signal Su, Sv, Sw is obtained by multiplying M by the q-axis current command IQ.
To the dead time correction circuit 23.

FIG. 2 shows the relationship between the U-phase current, the q-axis current command, and the U-phase magnetic pole position signal UM when the torque is positive.
Shows the relationship between the U-phase current, the q-axis current command, the U-phase magnetic pole position signal UM and the magnetic pole position signals VM and WM at the time of negative torque.

The dead time correction circuit 23 converts the reference PWM pulse signals S1U, S1V, S1W output from the PWM pulse generation circuit 21 according to the signs of the signals Su, Sv, Sw output from the polarity discrimination switching circuit 22. When the pulse width is positive, the pulse is corrected so as to have a wide pulse width by the correction amount Tλ. As a result, the dead time correction circuit 23 outputs S5
U, S5V and S5W output signals are obtained.

Further, the output signals S5U, S5V, S5W of the dead time correction circuit 23 are provided with a dead time Td by the dead time circuit 24 so that the upper and lower arms constituting the main circuit of the inverter are not short-circuited, and the gate signals U +, U
−, V +, V−, W +, W− are output.

Reference numeral 25 denotes a CPU which can be operated by a microcomputer or the like, reference numeral 26 denotes a data bus, and reference numeral 27 denotes an operation block. That is, the portion surrounded by the operation block 27 described above can be realized by hardware or software.

Further, the correction amount Tλ of the dead time correction circuit 23 and the dead time Td of the dead time circuit 24
U25 can be rewritten on software via data bus 26. FIG. 4 shows an embodiment of the polarity discrimination switching circuit 22 for achieving the first object of the present invention. In the figure, only the U phase is described, and the V phase and the W phase are the same and will not be described. That is, in the figure, the q-axis current command IQ and the output of the magnetic pole position detecting means UM are multiplied by a multiplier 2.
The output signal SU outputs a high-level signal if the result is positive, and outputs a low-level signal if the result is negative. Further, a q-axis feedback current Iqf may be used instead of the q-axis current command IQ.

Next, the dead time correction circuit 2 in FIG.
FIG. 5 shows a specific configuration of the third and dead time circuits 24. The pulse width correction performed by these circuits is shown in FIG.
7 and the U-phase inverter circuit shown in FIG. In the inverter circuit 6, a case where the load current iL flows from the inverter 3 to the synchronous motor 1 is defined as a positive direction of the current, and a case where the load current iL is opposite is defined as a negative direction. FIG. 6 is a time chart when the load current iL is positive, and FIG. 7 is a time chart when the load current iL is negative.

First, the case where the load current iL flows in the positive direction will be described. 8, both the transistor Tru and the transistor Trx in the inverter 6 are OFF.
At this time, the load current iL flows in the positive direction via the diode Dx in order to keep the motor current from flowing from the inverter 6 to the synchronous motor 1 side. Therefore, the motor terminal u
Is fixed to a negative power source and is shorter than the actual motor current. Therefore, it is necessary to add a time longer than the U-phase reference PWM pulse signal by a time Tλ for correction.

In FIG. 5, the reference PWM pulse signal S1U of the U phase is obtained as a signal S2U delayed by Tλ via the delay circuit 29 of the dead time correction circuit 23. Then, when the load current flows in the positive direction, the output signal SU of the polarity discrimination switching circuit 22 becomes high level, the AND circuit 31 is enabled, and the output of the OR circuit 30 is selected.

The output signal of the OR circuit 30 is the signal S1U
S5U output from the OR circuit 34 is an output signal of the dead time correction circuit 23, and the signal S5U is an input signal of the dead time circuit 24.

The dead time circuit 24 further includes a delay circuit 3
5, a signal S6U delayed by the time Td is obtained. Here, the AND circuit 36 takes the logical product of the signal S5U and the signal S6U and outputs it as a gate signal U +, and the NOR circuit 37 inverts the logical sum of the signal S5U and the signal S6U and outputs the gate signal U−.

Next, the case where the load current iL flows in the negative direction will be described. In FIG. 8, when the transistor Tru and the transistor Trx are both OFF, the load current iL flows in the negative direction via the diode Du in order to keep the motor current flowing from the synchronous motor 1 to the inverter 6. For this reason, the motor terminal u is fixed to the positive power supply, and the motor terminal u becomes larger than the actual motor current. Therefore, it is necessary to make correction by setting the time shorter than the U-phase reference PWM pulse signal by the time Tλ.

In FIG. 5, the output signal SU of the polarity discrimination switching circuit 22 becomes low level, and the AND circuit 33 becomes effective, thereby selecting the output signal of the AND circuit 32. AND
Since the circuit 32 takes the logical product of the signal S1U and the signal S2U, the signal S5U output at the timing shown in FIG. 7 is obtained. This signal S5U becomes the output signal of the dead time correction circuit 23, and the signal S5U is the dead time circuit 24. Input signal.

Further, in the dead time circuit 24, the delay circuit 3
5, a signal S6U delayed by the time Td is obtained. Here, the AND circuit 36 takes the logical product of the signal S5U and the signal S6U and outputs it as a gate signal U +, and the NOR circuit 37 inverts the logical sum of the signal S5U and the signal S6U and outputs the gate signal U−.

FIG. 9 shows another embodiment of the polarity discrimination switching circuit 22 in which an ENOR logic circuit is used instead of FIG. The sign signal IQS of the q-axis current command IQ and the detection output UM of the magnetic pole position detecting means 11 are generated by an ENOR circuit 38.
, And constitutes a polarity determination switching circuit 22
The circuit 38 outputs a signal SUI. That is, FIG.
As shown in (1), the signal IQS is at a high level when the q-axis current command IQ is positive, and is at a low level when the q-axis current command IQ is negative. Then, the signal SUI is changed to the signal SU in FIG.
If this is used, the same result as in the first embodiment can be obtained.

Further, a q-axis feedback current Iqf may be used instead of the q-axis current command IQ.

Next, a second embodiment of the present invention, which is another embodiment when the load condition is close to no load, will be described.
That is, as shown in FIG. 11, the q-axis current command IQ becomes minute, and the addition of noise or the like or the vibration of the control system sometimes makes it difficult to determine the polarity of the q-axis current as shown in the signal SUI. Therefore, the rotational speed command and the magnetic pole position detector 2 which can judge whether the torque is positive or negative with little influence of noise.
The dead time is corrected based on the detection output of the above.

FIG. 1 shows another embodiment of the polarity discrimination switching circuit 22.
It is shown in FIG. In this embodiment, the rotational speed command N is multiplied by the output signal UM of the magnetic pole position detection circuit 11 by the multiplier 39, and the result is set as SUM. If the multiplication result SUM is positive, a high-level signal is output, and if negative, a low-level signal is output. If this signal SUM is similarly used as the signal SU in the circuit configuration shown in FIG. 5, the same result as in the first embodiment can be obtained.

FIG. 13 shows another embodiment of the polarity discrimination switching circuit 22. In this embodiment, an ENOR logic circuit 40 is used instead of the multiplier shown in FIG. At this time, as shown in FIG. 14, the sign signal NS of the rotation speed command N is at a high level when the value of the rotation speed command N is positive, and is at a low level when the value of the rotation speed command N is negative.

The sign signal NS of the rotational speed command N and the output signal UM of the magnetic pole position detection circuit 11 are input to the ENOR circuit 40, and the signal SUM is output from the ENOR circuit 40 constituting the polarity discrimination switching circuit 22. By making the signal SUM the signal SU in the circuit configuration shown in FIG. 5 in the same manner as in the above embodiment, it is possible to stably correct the dead time.
Note that a rotation speed feedback Nf may be used instead of the rotation speed command N.

A third embodiment of the present invention will be described, which is a third embodiment of the present invention in which when the dead time is corrected based on the rotational speed command, the speed response is poor with respect to a load change. That is, in the present embodiment, as shown in FIG. 15, the result of multiplying the shaft current command IQ and the output signal UM of the magnetic pole position detection circuit 11 by the multiplier 41 is stored, and the rotational speed command N and the magnetic pole command N are stored. The result SUN obtained by multiplying the output signal UM of the position detection circuit 11 by the multiplier 42 is stored. Note that 43 is a load condition detection circuit, and 44 is a switch.

The load condition detection circuit 43 compares the q-axis current command with a specified value, controls the switching of the switch 44 according to the magnitude of the value, and selects the output signal of either the multiplier 41 or the multiplier 42. Do. That is, the switch 44 switches so as to output the signal SUI when the load condition is close to no load and the q-axis current command is smaller than the specified value, and to output the signal SUN when the q-axis current command is larger than the specified value. Can be

The signal SU is an output signal of the polarity discrimination switching circuit 22, and the same result as in the first embodiment can be obtained by using this signal as the input signal SU in the circuit configuration shown in FIG.

FIG. 16 shows another embodiment of the polarity discrimination switching circuit 22. In this embodiment, the multiplier 41 shown in FIG.
The configuration is such that ENOR circuits 45 and 46 are used in place of 42. That is, the aforementioned q-axis current command IQ
Sign signal IQS and the output signal U of the magnetic pole position detection circuit 11
M is input to the ENOR circuit 45, and the ENOR circuit 45
The signal SUI is output.

The sign signal NS of the rotation speed command N and the output signal UM of the magnetic pole position detection circuit 11 are
6 and the signal SUM is output from the ENOR circuit 46. 47 is a load condition detection circuit, 48 and 49 are AND circuits, and 50 is an OR circuit.

The load condition detection circuit 47 compares the q-axis current command with a specified value and outputs a high-level signal or a low-level signal depending on the magnitude of the value. That is, the load condition detection circuit 47 outputs a low level signal when the load condition is close to no load and the q-axis current
The input terminal of the D circuit 49 is selected, and the output signal SUM of the ENOR circuit 46 is selected and output via the OR circuit 50.

On the other hand, when the q-axis current command is larger than the specified value, the load condition detecting circuit 47 outputs a high level signal, selects the input terminal of the AND circuit 48, and selects the ENOR circuit 45
And outputs it via the OR circuit 50. The signal SU is an output signal of the polarity discrimination switching circuit 22, and is the input signal SU in the circuit configuration shown in FIG.
By doing so, the same result as in the first embodiment can be obtained.

[0077]

According to the present invention, magnetic pole detection for outputting three-phase square waves UM, VM, WM indicating the magnetic pole positions of a rotor directly connected to a synchronous motor and having the same phase as the induced voltage and having a phase difference of 120 degrees from each other. Since the three-phase square waves UM, VM and WM outputs of the transformer are multiplied by the sign of the q-axis current command, the polarity of the phase current of the synchronous motor is determined and the dead time is corrected. , The dead time compensation can be easily performed.

According to the present invention, the synchronous motor is directly connected to the rotational speed detector, and the rotational speed feedback signal Nf or the sign of the rotational speed command N detected from the rotational speed detector and the output signal of the magnetic pole detector are output. , The dead time is corrected by determining the polarity of the phase current of the synchronous motor, so that even if the load condition is close to no load and the q-axis current becomes very small, noise and the like are added. It is easy to determine the polarity of the current of the synchronous motor due to the vibration of the motor and the control system, correct the dead time, reduce the torque pulsation, improve the motor efficiency, and improve the dead time of the synchronous motor. Time compensation can be performed with high accuracy.

Further, according to the present invention, the magnitude of the q-axis current command or the detected value of the q-axis current is determined, and when they are larger than the specified values, the three-phase square waves UM, VM, WM output and the q-axis current The dead time is corrected by multiplying the command or the sign of the q-axis current detection value to determine the polarity of the phase current of the synchronous motor, and the magnitude of the q-axis current command or the q-axis current detection value is a specified value. If smaller, the output signal of the magnetic pole detector and the rotation speed command N or the rotation speed feedback signal Nf
Since the configuration is such that the polarity of the phase current of the synchronous motor is determined by multiplying by the sign of and the dead time is corrected,
It is possible to provide dead time correction that is significant for achieving high response in a synchronous motor.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a control device for a synchronous motor according to the present invention.

FIG. 2 is a time chart showing the operation principle of the synchronous motor control device according to the present invention.

FIG. 3 is a time chart showing the operation principle of the control device for a synchronous motor according to the present invention.

FIG. 4 is a circuit diagram showing a configuration of one embodiment of a polarity discrimination switching circuit in FIG. 1;

FIG. 5 is a circuit diagram showing a specific configuration of a dead time correction circuit and a dead time circuit in FIG. 1;

FIG. 6 is a time chart showing the operation of the dead time correction circuit and the dead time circuit in FIG. 5;

FIG. 7 is a time chart showing operations of the dead time correction circuit and the dead time circuit in FIG. 5;

FIG. 8 is a circuit diagram showing a configuration of a main circuit of the inverter in FIG. 1;

FIG. 9 is a circuit diagram showing a configuration of another embodiment of the polarity discrimination switching circuit in FIG. 1;

FIG. 10 is a waveform diagram showing a relationship between a q-axis current command and a sign signal IQS of the q-axis current command IQ.

FIG. 11 is a time chart showing an operation state of each unit of the control device for the synchronous motor when the q-axis current command is small.

FIG. 12 is a circuit diagram showing a configuration of another embodiment of the polarity discrimination switching circuit in FIG. 1;

FIG. 13 is a circuit diagram showing a configuration of another embodiment of the polarity discrimination switching circuit in FIG. 1;

FIG. 14 is a waveform diagram showing a relationship between a rotation speed command N and a sign signal NS of the rotation speed command N.

FIG. 15 is a circuit diagram showing a configuration of another embodiment of the polarity discrimination switching circuit in FIG. 1;

FIG. 16 is a circuit diagram showing a configuration of another embodiment of the polarity discrimination switching circuit in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Synchronous motor 2 Magnetic pole position detector 3 Rotation detector 4 Current detector 5 Current detector 6 Inverter 7 Commercial power supply 8 Rectifier 9 A / D converter 10 Three-phase / two-phase conversion circuit 11 Magnetic pole position detection circuit 12 sinθ / cosθ Table 13 Rotation detection circuit 14 Adder 15 Adder 16 Adder 17 Speed control operation circuit 18 q-axis current control operation circuit 19 d-axis current control operation circuit 20 Vector operation circuit 21 PWM pulse generation circuit 22 Polarity discrimination switching circuit 23 Dead time Correction circuit 24 Dead time circuit 25 CPU 26 Data bus 27 Operation block 28 Multiplier 39 Multiplier 41 Multiplier 42 Multiplier 29 Delay circuit 35 Delay circuit 43 Load condition detection circuit 47 Load condition detection circuit 44 Switching circuit 30 OR circuit 34 OR Circuit 50 OR circuit 31 AND circuit 32 AN D circuit 33 AND circuit 36 AND circuit 48 AND circuit 49 AND circuit 37 NOR circuit 38 ENOR circuit 40 ENOR circuit 45 ENOR circuit 46 ENOR circuit

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hiroyuki Tomita 7-1-1, Higashi-Narashino, Narashino-shi, Chiba Hitachi, Ltd. Narashino Plant (56) References JP-A-3-1644071 (JP, A) JP-A-1-321865 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02P 5/408-5/412 H02P 7/628-7 / 632 H02P 21/00 H02M 7/42-7/98 H02P 6/00-6/02

Claims (6)

(57) [Claims] 1. An arm short-circuit of a switching element constituting a main circuit of the PWM inverter by delaying the PWM signal supplied to a PWM inverter which outputs a variable voltage at a variable frequency based on a PWM signal for driving a synchronous motor. A method for controlling a synchronous motor that corrects a dead time set by a dead time setting circuit to prevent the occurrence of a torque, wherein a torque determined based on a rotation detection value of a rotor of the synchronous motor and a rotation speed command of the synchronous motor. A current polarity of a phase current of the synchronous motor is determined based on a current command value and a magnetic pole position detection value of a rotor in the synchronous motor, and the PWM signal and a determined current polarity of a phase current of the synchronous motor are determined. A synchronous power supply characterized in that a dead time set by a dead time setting circuit is corrected. Control method of the machine. 2. An arm short circuit of a switching element forming a main circuit of the PWM inverter by delaying the PWM signal supplied to a PWM inverter that outputs a variable voltage at a variable frequency based on a PWM signal that drives a synchronous motor. A synchronous motor control method for correcting a dead time set by a dead time setting circuit to prevent the synchronous motor based on a rotational speed command value of the synchronous motor and a detected magnetic pole position of a rotor in the synchronous motor. A synchronous motor for determining a current polarity of a phase current of the motor, and correcting a dead time set by the dead time setting circuit based on the PWM signal and the determined current polarity of the phase current of the synchronous motor. Control method. 3. An arm short-circuit of a switching element constituting a main circuit of the PWM inverter by delaying the PWM signal supplied to a PWM inverter that outputs a variable voltage at a variable frequency based on a PWM signal for driving a synchronous motor. A method for controlling a synchronous motor that corrects a dead time set by a dead time setting circuit to prevent the occurrence of a torque, wherein a torque determined based on a rotation detection value of a rotor of the synchronous motor and a rotation speed command of the synchronous motor. When it is determined that the current command value is large, the current polarity of the phase current of the synchronous motor is obtained based on the torque current command value and the detected magnetic pole position of the rotor in the synchronous motor, and the torque current command value is small. Is determined based on the rotational speed command value of the synchronous motor and the magnetic pole position detection value. Obtains a current polarity of a phase current of the motor, the PW
A method for controlling a synchronous motor, wherein the dead time set by the dead time setting circuit is corrected based on the M signal and the current polarity of the obtained phase current of the synchronous motor. 4. A PWM inverter control device for outputting a variable voltage at a variable frequency based on a PWM signal for driving a synchronous motor, wherein the PWM signal is delayed to form a main circuit of the PWM inverter. In a synchronous motor control device having a dead time setting circuit for preventing an element short circuit, a magnetic pole position detecting means for detecting a magnetic pole position of a rotor in the synchronous motor, and a rotational speed of a rotor in the synchronous motor. Rotation speed detection means for detecting, rotation speed command means for commanding the rotation speed of the synchronous motor, speed control means for outputting a torque current command based on the rotation detection value and the rotation speed command, the torque current command Current polarity determination for obtaining the current polarity of the phase current of the synchronous motor based on the value and the magnetic pole position detection value And a dead time correction means for correcting the dead time set by the dead time setting circuit based on the PWM signal and a signal indicating the current polarity of the phase current of the synchronous motor output from the current polarity determination means. A control device for a synchronous motor, comprising: 5. A PWM inverter control device for outputting a variable voltage at a variable frequency based on a PWM signal for driving a synchronous motor, wherein the PWM signal is delayed to form a main circuit of the PWM inverter. In a synchronous motor control device having a dead time setting circuit for preventing an element short circuit, a magnetic pole position detecting means for detecting a magnetic pole position of a rotor in the synchronous motor, and a rotational speed of a rotor in the synchronous motor. Rotation speed detection means for detecting, rotation speed command means for commanding the rotation speed of the synchronous motor, speed control means for outputting a torque current command based on the rotation detection value and the rotation speed command, the rotation speed command Current polarity determining means for determining the current polarity of the phase current of the synchronous motor based on the magnetic pole position value and the detected magnetic pole position value. And dead time correction means for correcting the dead time set by the dead time setting circuit based on the PWM signal and a signal indicating the current polarity of the phase current of the synchronous motor output from the current polarity determination means. A control device for a synchronous motor, comprising: 6. A control device for a PWM inverter for outputting a variable voltage at a variable frequency based on a PWM signal for driving a synchronous motor, wherein the PWM signal is delayed to constitute a main circuit of the PWM inverter. In a synchronous motor control device having a dead time setting circuit for preventing an element short circuit, a magnetic pole position detecting means for detecting a magnetic pole position of a rotor in the synchronous motor, and a rotational speed of a rotor in the synchronous motor. Rotation speed detection means for detecting, rotation speed command means for commanding the rotation speed of the synchronous motor, speed control means for outputting a torque current command based on the rotation detection value and the rotation speed command, the torque current command Torque current command value determining means for determining the magnitude of the value; When it is determined that the torque current command value is large, the current polarity of the phase current of the synchronous motor is obtained based on the torque current command value and the magnetic pole position detection value, and when it is determined that the torque current command value is small. Means for determining the polarity of the phase current of the synchronous motor based on the rotational speed command value and the magnetic pole position detection value; phase current of the synchronous motor output from the PWM signal and the current polarity determination means A dead time correction means for correcting a dead time set by the dead time setting circuit based on a signal indicating the current polarity of the synchronous motor.