JPH01150494U - - Google Patents

Description

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of a control device for a brushless DC motor according to the present invention, Fig. 2 is a perspective view showing the main parts of the brushless DC motor shown in Fig. Figure 4 is a time chart showing various signals until reaching steady rotation. Figure 4 is a diagram showing the relationship between time and frequency in an exponential frequency signal. Figure 5 is a time chart showing various signals after reaching steady rotation. be. 1... Brushless DC motor, 6... PLL servo circuit, 7... FG, 15... Changeover switch circuit, 16
...exponential frequency signal generator, 17...timer,
19...Excitation timing signal forming circuit.

Claims (1)

[Scope of Claim for Utility Model Registration] A motor drive circuit that supplies excitation current to an excitation coil and a frequency generator, and a speed control means that controls the rotational speed of the rotor to a constant value, and the frequency increases exponentially. Exponential frequency signal generating means for generating an exponential frequency signal; Excitation timing signal forming means for forming an excitation timing signal synchronized with the exponential frequency signal or the frequency generator signal and supplying the excitation timing signal to the motor drive circuit. and a signal selection means for selectively supplying the exponential frequency signal and the frequency generator signal to the excitation timing signal forming means, and after starting, the exponential frequency is maintained until the rotor approaches a steady rotation speed. signal selection for supplying a signal to the excitation timing signal forming means and controlling the signal selection means to supply the frequency generator signal to the excitation timing signal forming means after the rotor approaches a steady rotation speed; A control device for a brushless DC motor, comprising a control means.