Electricity: measuring and testing – Impedance – admittance or other quantities representative of... – Lumped type parameters
Reexamination Certificate
2001-11-29
2004-03-02
Cuneo, Kamand (Department: 2829)
Electricity: measuring and testing
Impedance, admittance or other quantities representative of...
Lumped type parameters
C318S254100, C318S434000, C318S132000, C701S066000, C701S102000
Reexamination Certificate
active
06700400
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a constant detecting apparatus for a brushless DC motor for detecting the inductance of a brushless DC motor comprising a rotor that has a permanent magnet and a stator that generates a rotating magnetic field that causes the rotation of the rotor, a control apparatus for a brushless DC motor, and a program for detecting the constant of a brushless DC motor.
2. Description of the Related Art
Conventionally, vehicles such as electric vehicles and hybrid vehicles are known that have installed a brushless DC motor using a permanent magnet to provide a magnetic field as a power source for vehicle travel.
A control apparatus for this kind of brushless DC motor is known that carries out feedback control such that, for example, a phase current supplied to each phase of a brushless DC motor is measured, and the measured value of the phase current is converted to an orthogonal coordinate system that rotates in synchronism with the rotor. The orthogonal coordinate system comprises, for example, a d axis current and a q axis current on a dq coordinate system where the direction of the flux of the rotor is the d axis (the torque axis) and the direction orthogonal to this d axis is the q axis (the magnetic field axis). In this control apparatus, the feedback control is carried out so that the difference between the command value and the measured value of the current is zero on this dq coordinate system.
Specifically, the d axis voltage command value and the q axis voltage command value on the dq coordinate system are calculated, for example, by a proportional integration (PI) operation from the differences between the command value and the observed value of the current on the dq coordinate axis, that is, the d axis current difference and the q axis current difference. Next, each of the voltage command values for the phase voltage supplied to each of, for example, three phases (the U phase, the V phase, and the W phase) of the brushless DC motor are calculated from the d axis voltage command value and the q axis voltage command value. In addition, each of these voltage command values is input as a switching command to the inverter formed by switching elements such as insulated-gate bipolar transistors (IGBTs), and the alternating current power for driving the brushless DC motor is output from the inverter depending on these switching commands.
In a control apparatus for a brushless DC motor according to the one example of the conventional art described above, a method is known wherein, for example, the d axis inductance and q axis inductance are calculated as parameters when the d axis current command value and the q axis current command value are calculated based on the torque command that depends on how much the driver of the vehicle maneuvers the accelerator.
However, in the control apparatus of the brushless DC motor described above, because of the presence, for example, of the phase delay characteristic of the position sensor for detecting the electromagnetic pole position of the rotor, there is the case in which the signal of the position sensor that represents a predetermined reference position presents a value that has shifted with respect to the true reference position as the number of rotations increases. Due to the shifting of the position sensor, there are the problems that errors occur in the phases of each of the current phases and the phases of each of the voltage phases, and that errors occur in the results of the calculation of the d axis inductance and the q axis inductance.
In addition, while the brushless DC motor is being rotated, the winding resistance value fluctuates along with the fluctuations in the temperature of the windings that are wound around the rotor, the induced voltage fluctuates along with the fluctuations in the temperature of the permanent magnet of the rotor, the iron loss fluctuates, or the like, and thereby there are the problems that errors occur in the voltage vector, and that errors occur in the results of the calculation of the d axis inductance and the q axis inductance.
Here, in the case that the d axis current command value and the q axis current command value are calculated based on a d axis inductance and a q axis inductance that include these errors, there are the problems that the precision of the initial response decreases, and that the responsiveness during feedback control deteriorates. Furthermore, because the actual operating condition cannot be adequately known, there is the concern that inconveniences such as a decrease in the operating efficiency and excess current may occur.
In addition, in methods that estimate each of the inductances by taking into consideration the amount of transient fluctuation of the d axis inductance and the q axis inductance, there are the problems that the amount of required memory must be increased in order to store each type of control data. In addition, the calculation processing becomes complex, the scale of the control apparatus increases, and the necessary cost is increased when the control apparatus is configured.
In consideration of the above-described problems, it is an object of the present invention to provide a constant detecting apparatus for a brushless DC motor wherein the necessary cost originating in configuring the apparatus and the programs is decreased and the initial response precision and readiness during control is increased, control apparatus for the brushless DC motor, and a program for detecting the constant of a brushless DC motor.
SUMMARY OF THE INVENTION
In order to attain the object of solving the above-described problems, in a first aspect of the present invention, a constant detecting apparatus for a brushless DC motor for detecting the inductance of a brushless DC motor comprising a rotor that has a permanent magnet and a multiphase stator that generates a rotating magnetic field that causes the rotation of the rotor is characterized in comprising a phase voltage detecting device (for example, the phase voltage detector
46
in the embodiment described below) for detecting the phase angle and the effective value of the phase voltage of the brushless DC motor and a phase current detecting device (for example, the phase current detector
47
in the embodiment described below) for detecting the phase angle and the effective value of the phase current and a position detecting device (for example, the position sensor
43
in the embodiment described below) for detecting the phase angle of the induced voltage from the magnetic pole position of the rotor and a rotation number detecting device (for example the rotation sensor
41
in the embodiment described below) for detecting the number of rotations; a phase resistance value calculating device (for example, step S
12
in the embodiment described below) for calculating the phase resistance value based on the temperature of the brushless DC motor and an induced voltage constant calculating device (for example, step S
24
in the embodiment described below) for calculating the induced voltage constant; a phase difference calculating device (for example, step S
14
and step S
17
in the embodiment described below) for calculating the voltage phase difference comprising the difference between the phases of the induced voltage and phase voltage and the current phase difference comprising the difference between the phases of the induced voltage and the phase current; a phase compensating value calculating device (for example, the step S
16
in the embodiment described below) for calculating the phase compensating value that compensates the voltage phase difference and the current phase difference based on the number of rotations; an iron loss calculating device (for example, steps S
20
to step S
27
in the embodiment described below) for calculating the iron loss of the brushless DC motor; an effective phase current calculating device (step S
28
in the embodiment described below) for calculating the effective phase current based on the ir
Chan Emily Y
Cuneo Kamand
Honda Giken Kogyo Kabushiki Kaisha
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