JPH0799884B2 - Variable speed control device for vehicle drive synchronous motor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a variable speed control device for a vehicle-drive synchronous motor,
More specifically, the present invention relates to a variable speed control device for a vehicle drive synchronous motor, which efficiently performs variable speed control of a permanent magnet type synchronous motor used for driving a vehicle.

[Technical Background of the Invention and Problems Thereof] Generally, a permanent magnet type synchronous motor used for driving a vehicle converts a DC voltage from a vehicle-mounted battery into an AC voltage by an inverter circuit and is driven by this AC voltage. However, variable voltage variable frequency control is performed to variably control the frequency and voltage of the AC voltage supplied to the electric motor in order to perform variable speed control of the electric motor with good response characteristics and high efficiency.
FIG. 4 is a block diagram of a conventional variable speed control device for a vehicle drive synchronous motor that employs such a control system.

In FIG. 4, the DC voltage of the vehicle-mounted battery 1 is converted into an AC voltage by the inverter 2, and the synchronous motor 3 is driven by the AC voltage. The synchronous motor 3 is used for a vehicle, and is controlled by a variable speed command signal A supplied from a variable speed command device 5 such as an accelerator. Further, in this case, the synchronous motor 3 is used. The rotation speed signal ω from the rotation speed sensor 4 for detecting the rotation speed is fed back, and drive control is performed in consideration of this rotation speed signal ω. That is, the variable speed command signal A from the variable speed command device 5 is the variable speed command signal A.
Is supplied to the function generator 6 which outputs a coefficient A ′ proportional to the rotation speed signal ω from the rotation speed sensor 4 and the input voltage / rotation speed coefficient (hereinafter, V / Abbreviated as F), that is, V that generates the coefficient γ
/ F is supplied to the generator 7. Then, the coefficient A ′ from the function generator 6 is multiplied by the coefficient γ from the V / F generator 7 by the multiplier 8 to calculate the applied command voltage ||, which is the three-phase sine wave. It is supplied to the generator 9.
The three-phase sine wave generator 9 is also supplied with the rotation speed signal ω from the rotation speed sensor 4, and the three-phase sine wave generator 9 receives the three-phase sine wave generator 9 according to the applied command voltage || and the rotation speed signal ω. Outputs a phase sine wave signal. This three-phase sine wave signal is supplied to one input of comparators 11, 12 and 13, respectively, and is supplied to the other input of the carrier triangular wave generator.
The amplitude is compared with the triangular wave signal from 10. As a result,
Each of the three-phase sine wave signals is pulse-width modulated and supplied to the inverter 2, whereby the DC voltage of the battery 1 is converted into a three-phase AC voltage to drive and control the synchronous motor 3.

In such control, V / F is controlled to be constant so that the generated torque is constant, and the input voltage is varied in proportion to the rotation speed of the synchronous motor 3. Therefore, there is a problem that the synchronous motor does not always operate at the operating point where the efficiency of the synchronous motor is maximum with respect to each torque value at each rotational speed, and the overall efficiency deteriorates.

[Object of the Invention] The present invention has been made in view of the above, and an object of the present invention is to enable control of a drive torque according to an accelerator depression amount at an operating point at which the maximum capacity of a synchronous motor is exhibited. Another object of the present invention is to provide a variable speed control device for a vehicle drive synchronous motor.

[Summary of the Invention] To achieve the above object, the present invention provides a synchronous electric motor for driving a vehicle, a rotational speed detecting means for detecting a rotational speed of the electric motor, and an accelerator depression amount according to an accelerator depression operation. An accelerator depression amount detecting means, a calculating means for calculating an applied voltage to the electric motor based on the rotation speed and the accelerator depression amount, a torque detecting means for detecting a generated torque in the electric motor, the rotation speed and A correction coefficient calculation means for calculating an applied voltage correction coefficient capable of correcting the applied voltage so as to obtain the maximum efficiency in the electric motor based on the generated torque, and the applied voltage correction coefficient calculated by the correction coefficient calculation means. Correction means for correcting the applied voltage based on the applied voltage, and a control means for driving the electric motor based on the applied voltage corrected by the correction means. Characterized in that it has and.

Embodiments of the Invention Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a variable speed control device for a vehicle driving synchronous motor according to an embodiment of the present invention. The variable speed control device for a synchronous motor shown in FIG. 1 drives and controls, for example, a synchronous motor used for a vehicle.
The configuration of each element shown in -13 is the same as that of FIG. 4,
A torque detector 14 and a coefficient generator 15 are newly added to this configuration.

The torque detector 14 is attached to the output shaft of the synchronous motor 3, detects the output torque T of the synchronous motor 3, and supplies the detected output torque T to the coefficient generator 15.

The coefficient generator 15 varies the input voltage to the synchronous motor 3, that is, the applied command voltage ||, in order to operate the synchronous motor 3 at maximum efficiency based on the rotation speed signal ω and the torque signal T of the synchronous motor 3. The input voltage correction coefficient δ is generated. For example, a ROM package including a semiconductor ROM memory is used, and the input voltage correction coefficient δ is stored in this ROM memory using the rotation speed signal ω and the torque signal T as parameters. It is composed. By inputting the rotation speed signal ω and the torque signal T to the coefficient generator 15, the input voltage correction coefficient δ corresponding to these inputs is output, and the input voltage correction coefficient δ is supplied to the multiplier 8. , By this, multiplier 8
As described above, the applied command voltage || composed of the product of the coefficient A'and the coefficient [gamma] is multiplied by the input voltage correction coefficient [delta] to correct the applied command voltage ||. Then, the corrected applied command voltage |
│'is the three-phase sine wave generator 9 and the comparators 11, 12, 13
It is supplied to the inverter 2 via the to control the synchronous motor 3.

By the way, when the rotation speed of the synchronous motor 3 is constant N ₀ ,
In the conventional method of controlling V / F to be constant, the torque-efficiency characteristic has a curve characteristic as shown in FIG. In this characteristic, the input voltage is V ₀ (V). put it here,
When the input voltage is varied within the range of V ₁ <V ₀ <V ₂ , the torque-efficiency characteristics are shown in FIG. 3 with respect to each voltage V ₁ , V ₀ , V ₂ by the curves a, b, and It changes as shown by c. That is, by changing the input voltage as V ₁ , V ₀ , V ₂ corresponding to the torque T for the same rotation speed N ₀ , the efficiency η of the synchronous motor 3 does not change the voltage, but is, for example, the voltage V _This is a significant improvement compared to when it is fixed at ₀ . In other words, if the input voltage V ₀ is fixed and controlled so that V / F is constant as in the conventional case, the torque T becomes 0 as shown by the curve b.
The efficiency η increases as the torque changes from tp to tp, but when the torque T changes from tp to t ₁ , the efficiency η extremely deteriorates, and when t ₁ or more, the step out occurs. On the other hand, by changing the input voltage as shown in FIG. 3 and using the envelope of the maximum efficiency point of the torque-efficiency characteristic at this time, that is, the envelope shown by OABC in FIG. Is something that can rise. By doing this, the third
As can be seen from the figure, the maximum torque point can be increased from t ₁ to t ₂ . Point C corresponding to this maximum torque point t ₂
Is a point determined by the current limit or temperature limit for the synchronous motor 3. Further, the input voltage V ₁ is the lower limit voltage that allows the synchronous motor 3 to operate stably, and is the voltage that shows the maximum efficiency among the input voltages.

As described above, in order to supply the synchronous motor 3 with the input voltage capable of generating the maximum efficiency η with respect to each rotation speed, that is, each torque T when the rotation speed signal ω is constant, first,
As shown in FIG. 3, various input voltages capable of generating the maximum efficiency for each torque T are obtained by using the rotation speed N as a parameter, and the input voltage corresponding to the applied command voltage || obtained from the multiplier 8 from this input voltage. The correction coefficient δ is calculated in advance. That is, the input voltage correction coefficient δ for each torque T and the rotation speed signal ω is obtained in advance, and this relationship is stored in the ROM memory in the table format as described above. By accessing this ROM memory using the rotation speed signal ω as an input signal, the input voltage correction coefficient δ corresponding to the input torque T and the rotation speed signal ω can be obtained.

Then, in this way, the torque signal T and the rotation speed signal ω
Similarly, the applied command voltage || obtained by the multiplier 8 is similarly corrected in the multiplier 8 by the input voltage correction coefficient δ obtained corresponding to the maximum efficiency for the torque signal T and the rotation speed signal ω. input voltage that can generate η,
That is, the applied command voltage || 'is obtained,
If the applied command voltage || 'is supplied to the inverter 2 via the three-phase sine wave generator 9 and the comparators 11, 12, 13 in the same manner as described above to control the synchronous motor 3, the synchronous motor 3 has the maximum efficiency η. It can work with.

[Effects of the Invention] As described above, in the present invention, since the synchronous motor is driven by the voltage applied to the synchronous motor based on the accelerator depression amount and the rotation speed of the synchronous motor, the torque generated in the synchronous motor is reduced. Since the driving torque depends on the accelerator depression amount, the driving torque of the vehicle can be controlled according to the accelerator depression amount.

Further, the applied voltage to the synchronous motor is corrected by the applied voltage correction coefficient calculated based on the rotational speed and the generated torque of the synchronous motor so that the maximum efficiency of the synchronous motor can be obtained. Can be controlled at the operating point where the maximum capacity of the synchronous motor is exhibited. As a result, it is possible to suppress an increase in power consumption by the synchronous motor while controlling the drive torque based on the driver's intention, and it is possible to obtain an effect that, for example, the travelable distance can be significantly extended.

[Brief description of drawings]

FIG. 1 is a block diagram of a variable speed control device for a vehicle-driving synchronous motor according to an embodiment of the present invention, and FIG. 2 is a characteristic diagram showing torque-efficiency characteristics of the synchronous motor with a constant rotation speed. Similar to FIG. 2, the figure is a characteristic diagram showing torque-efficiency characteristics of the synchronous motor when the rotation speed is constant and the input voltage is a parameter. FIG. 4 is a conventional variable speed control device for a vehicle drive synchronous motor. It is a block diagram of. 1 ... Battery, 2 ... Inverter 3 ... Synchronous motor, 4 ... Rotation speed sensor 5 ... Variable speed commander, 14 ... Torque detector 15 ... Coefficient generator

Claims (1)

[Claims] 1. A synchronous electric motor for driving a vehicle, a rotational speed detecting means for detecting a rotational speed of the electric motor, an accelerator depression amount detecting means for detecting an accelerator depression amount according to an accelerator depression operation, and the rotation speed. And a calculating unit that calculates a voltage applied to the electric motor based on the accelerator depression amount, a torque detecting unit that detects a generated torque in the electric motor, and a maximum efficiency in the electric motor based on the rotation speed and the generated torque. Correction coefficient calculating means for calculating an applied voltage correction coefficient capable of correcting the applied voltage so as to obtain, and correction means for correcting the applied voltage based on the applied voltage correction coefficient calculated by the correction coefficient calculating means. And a control means for driving the electric motor based on the applied voltage corrected by the correction means. Variable-speed control device for electric motors.