JPH0622594A - Driving method for symchronous motor - Google Patents

Abstract

PURPOSE:To eliminate windings for detecting pole position by outputting phase terminal voltage commands from a circuit for distributing a gate signal to a switching element, and using a magnetic flux signal obtained by integrating a multiplied value of the command and a DC input voltage detected value as a position signal of a rotor pole. CONSTITUTION:A three-phase synchronous motor 20 has stator windings 21 in which powers are supplied through a three-phase inverter 20 having three- phase bridge-connected switching elements to convert a DC power from a DC current source 1 into three-phase AC. An output phase of the inverter is converted in response to a rotor pole position of the motor 20. In this case, U-phase, V-phase and W-phase terminal voltage command signals of the inverter 10 are output by a logic circuit 28 of a control circuit 24, and the command signals are multiplied by an input current voltage value of the inverter 10 to be detected by a voltage sensor 33. The multiplied result is integrated by an integrator 26, and a magnetic flux signal obtained therefrom is output to the inverter 10 as a position signal of the rotor pole.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention has three switching elements.
The DC power is converted into three-phase AC by the power converter connected to the phase bridge and supplied to the stator winding of the three-phase synchronous motor.
The present invention relates to a synchronous motor driving method for switching the output phase of the power converter according to the rotor magnetic pole position of the synchronous motor.

[0002]

2. Description of the Related Art FIG. 6 shows a conventional drive circuit for a synchronous motor.
This is an example. In the figure, 1 is a constant voltage direct current source (for example, a battery), τ ^* is a torque command, I
^* Is a current command, 2 is a converter for converting the torque command τ ^* into a current command I ^* , 10 is a three-phase inverter (shown in FIG. 7), and 20A is a permanent magnet type three-phase synchronous motor SM. Reference numeral 21 denotes a stator winding of the synchronous motor (main winding having U-, V-, and W-phase windings), 22 a magnet rotor made of a permanent magnet,
Reference numeral 23 is a detection winding (auxiliary winding having u-, v-, and w-phase windings) for detecting the magnetic pole position. Reference numeral 24 is a control circuit for the three-phase inverter 10. 25 is a Δ → Y converter, 26 is an integrator, 2
Reference numeral 7 is a polarity discriminator, and 28 is a logic circuit. Detection winding 23
Is a low impedance winding with a small number of turns. Figure 7
In the above, T _{r1 to} T _r6 are transistors, D is a diode, and g _{1 to} g ₆ are base signals supplied to the bases of T _{r1 to} T _r6 , respectively.

In this structure, when the magnet rotor 22 rotates, the angle of the permanent magnet with respect to the u-phase winding of the detection winding 23 changes, so that the amount of magnetic flux Φ interlinking with the u-phase winding of the detection winding 23. Changes, and a voltage e _U is induced in the u-phase winding. The integrator 26 integrates the voltage e _U, and outputs the magnetic flux signal [Phi _U of sin waveform. The polarity determiner 27 determines whether the magnetic flux signal Φ _U is positive or negative and gives a determination signal to the logic circuit 28. When the logic circuit 28 receives the positive magnetic flux signal Φ _U , it outputs a base signal (shown in FIG. 8) that causes the switching elements T _r1 and T _r6 of FIG. 7 to conduct at a conduction angle of 120 ⁰ , and the negative magnetic flux signal. When Φ _U is input, a base signal that causes the switching elements T _r1 and T _r6 of FIG. 5 to conduct at a conduction angle of 120 ⁰ is output. The voltages induced in the v-phase winding and the w-phase winding are processed in the same manner, and the logic circuit 28 distributes the base signal to the switching elements T _{r2 to} T _{r6 in} a predetermined order based on the processing result.

The above-mentioned conventional device takes out the change of the magnetic pole position of the rotor 22 as the change of the magnetic flux amount Φ, indirectly detects the magnetic pole position of the rotor 22 based on the change of the magnetic flux amount Φ, and detects the output phase of the inverter 10. This is a switching method, and since the auxiliary winding 23 for magnetic pole position detection is provided in the synchronous motor 20A, there is a problem that the synchronous motor 20A becomes expensive and large in size.

Therefore, the present inventors have found that the synchronous motor 20
However, in the case of a high speed machine (for example, 100.000 rpm, 1.67 KHz) in which the number of turns of the stator winding 21 is small, as shown in FIG. 5, the stator in which the magnetic flux of the permanent magnet of the rotor 22 is interlinked. the winding induced voltage V _M and the winding resistance R by the voltage drop V _R and the terminal voltage V of the stator winding 21 is the vector sum of the winding 21 is substantially the same phase winding induced voltage V _M Focusing on, the experiment confirmed that a magnetic flux signal obtained by integrating the terminal voltage V can be used instead of the magnetic flux signal obtained by integrating the detection voltage of the detection winding 23.

FIG. 3 shows the circuit configuration used in this experiment. In FIG. 3, reference numeral 20 denotes a permanent magnet type three-phase synchronous motor SM. This synchronous motor 20 has a magnetic pole position detection winding (auxiliary winding) 23 described in the description of the conventional example.
Is not prepared. A three-phase transformer PT 30 detects the terminal voltage V of the stator winding 21 of the synchronous motor 20 and supplies the detected voltage to the control circuit 24.

FIG. 4 shows a one-phase equivalent circuit of the stator winding 21 of the synchronous motor 20, where V _R is the winding resistance R.
, V _M is the winding induced voltage, and L is the winding inductance.

In this structure, the transformer 30 detects the terminal voltage V of each phase of the stator winding 21. This terminal voltage V
Is the vector sum of the winding induced voltage V _M of the stator winding 21 where the magnetic flux of the permanent magnet of the rotor 22 interlinks and the voltage drop V _R due to the winding resistance R, as shown in FIG. since the synchronous motor 20 is R, smaller low impedance machines of L, and the V _M and V, as shown, it is substantially equal to the vector values.

The terminal voltage V is integrated and the magnetic flux signal (Φ _A
And the stator winding 21 is the detection winding 23
Since it is a low-impedance winding like the above, the change of the magnetic flux signal Φ _{A will be} a change almost in synchronism with the magnetic flux signal (referred to as Φ _B ), similar to the conventional case having the auxiliary winding 21. Moreover, the output phase of the inverter 10 can be switched according to the change of the magnetic pole position of the rotor 22.

[0010]

In the case of the driving method shown in FIG. 3, since the conventional auxiliary winding 23 is not necessary,
The size of the synchronous motor can be reduced and the cost can be reduced, but there is a drawback in that the transformer 31 is required and the transformer 31 must be connected.

The present invention has been made in order to solve this problem. Although the magnetic pole position of the rotor is indirectly detected, it is not only necessary to provide the above-mentioned auxiliary winding in the synchronous motor, but also the magnetic pole position is not required. An object of the present invention is to provide a method of driving a synchronous motor that does not require any detection means for detecting electrical quantities for detection.

[0012]

In order to achieve the above object, the present invention according to claim 1 converts a direct current into a three-phase alternating current by a power converter formed by connecting a switching element to a three-phase bridge, and the three-phase same. In the driving method of the synchronous motor, which supplies the stator winding of the stationary motor and switches the output phase of the power converter in accordance with the rotor magnetic pole position of the synchronous motor, the gate from the circuit that distributes the gate signal to the switching element. Each phase terminal voltage command of the same time width as the signal is taken out, and the magnetic flux signal obtained by integrating the product value of each phase terminal voltage command and the DC input voltage detection value of the power converter is used as the position signal of the rotor magnetic pole. did.

In the second aspect, a constant is used instead of the DC input voltage detection value of the power converter.

According to a third aspect of the present invention, the synchronous motor is a low-impedance high-speed machine.

[0015]

In the present invention, the magnetic flux signal is obtained by integrating the multiplication value of the voltage command for each phase terminal taken out from the circuit for distributing the gate signal to the switching element and the detected value of the DC input voltage of the power converter. The signal changes substantially in synchronization with the magnetic flux signal obtained by integrating the induced voltage of the conventional auxiliary winding.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 20 denotes a permanent magnet type three-phase synchronous motor SM, but this synchronous motor 20 does not include the magnetic pole position detection winding 23 described in the description of the conventional example. Reference numeral 33 is a voltage sensor for detecting the input DC voltage E of the inverter 10. U ^*, V ^*, W ^* is U-phase taken out from the logic circuit 28, V-phase, a W phase terminal voltage command signal (120 ⁰ conduction waveform), multiplied by the detected value of the voltage sensor 33 at the multiplier 34 Then, the output of the multiplier 34 is supplied to the integrator 26. Other configurations are the same as those in FIG.

The three-phase synchronous motor 20 has a stator winding 2
A high-speed machine with a small number of turns per 1 (for example, 100.000
rpm, 1.67 KHz).

In the example of FIG. 3, the terminal voltage V of the stator winding 21 is integrated to obtain the magnetic flux signal Φ _A. This terminal voltage V is the input voltage E of the inverter 10 and the switching element of the inverter 10. equal to the value of the product of the oN period t _on / OFF period t _of.

Terminal voltage V = inverter input voltage E × t _on / t _of (1) In this embodiment, the logic circuit 28 uses U-phase, V-phase, and W-phase terminal voltage command signals U ^* , V ^* , and W ^*. Is generated and the product of the terminal voltage command signals U ^* , V ^* , W ^* and the detection voltage E of the voltage sensor 33 is integrated to obtain the magnetic flux signal Φ _A.

Therefore, in this embodiment, the transformer 30 shown in FIG.
Becomes unnecessary.

In the above embodiment, the voltage sensor 33 is provided to detect the input voltage E of the inverter 10. However, when a battery is used as the direct current source 1, the input voltage E is a substantially constant value. Therefore, as shown in FIG.
The magnetic flux signal Φ _A may be obtained by integrating the product value of the terminal voltage command signals U ^* , V ^* , W ^* and the constant K _E.

[0023]

As described above, according to the present invention, it is not only necessary to provide the above-mentioned auxiliary winding or the like in the synchronous motor, but also it is necessary to provide any means for detecting various electrical quantities for detecting the magnetic pole position of the rotor. Therefore, the synchronous motor device including the drive circuit can be made smaller and cheaper than the conventional device.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a second embodiment of the present invention.

FIG. 3 is a circuit diagram showing an example of a drive circuit for a synchronous motor.

FIG. 4 is a diagram showing an equivalent circuit of a synchronous motor.

FIG. 5 is a voltage vector diagram of the synchronous motor.

FIG. 6 is a circuit diagram of a conventional drive circuit for a synchronous motor.

FIG. 7 is a circuit diagram of a three-phase inverter.

FIG. 8 is a diagram showing a base signal of a three-phase inverter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 DC current source 2 Converter 10 Three-phase inverter 20 Synchronous motor 21 Stator winding 22 Rotor 24 Control circuit 26 Integrator 27 Polarity discriminator 28 Logic circuit 33 Voltage sensor 34 Multiplier

Claims (3)

[Claims] 1. A power converter formed by connecting switching elements to a three-phase bridge to convert direct current into three-phase alternating current.
In the method of driving a synchronous motor, which supplies the stator winding of a phase synchronous motor and switches the output phase of the power converter in accordance with the rotor magnetic pole position of the synchronous motor, a circuit for distributing a gate signal to the switching element is used. Take out each phase terminal voltage command of the same time width as the gate signal, and use the magnetic flux signal obtained by integrating the product of this phase terminal voltage command and the DC input voltage detection value of the power converter as the position signal of the rotor magnetic pole. And a method of driving a synchronous motor. 2. The method for driving a synchronous motor according to claim 1, wherein a constant is used instead of the DC input voltage detection value of the power converter. 3. The method for driving a synchronous motor according to claim 1, wherein the synchronous motor is a high-speed machine having a low impedance.