Low frequency drive control circuit and method for driving an inductive load
View Patent ↗According to one embodiment, a low frequency drive control circuit for use with an inductive load comprises a comparator configured to receive a high frequency signal at a first input and a smoothly varying low frequency signal for modulating the high frequency signal at a second input. The comparator is further configured to produce a pulse width modulated output of the low frequency drive control circuit for use in generating a smoothly varying low frequency load current in the inductive load. In one embodiment, the inductive load can comprise a DC brushed motor. In one embodiment, the low frequency drive control circuit can be implemented as part of an integrated circuit further comprising a switching circuit configured to use the pulse width modulated output of the comparator to generate the smoothly varying low frequency load current, which may be a substantially sinusoidal load current, for example.
1. A low frequency drive control circuit for use with an inductive load, said low frequency drive control circuit comprising:
a comparator configured to receive a high frequency signal at a first input and a low frequency signal for modulating said high frequency signal at a second input;
said comparator further configured to produce a pulse width modulated output of said low frequency drive control circuit for use in generating a low frequency load current in said inductive load;
wherein said comparator is configured to produce a signal of low frequency pulses as said pulse width modulated output, each of said low frequency pulses including a plurality of high frequency signal variations.
2. The low frequency drive control circuit of claim 1 , further comprising a low frequency signal generator for generating said low frequency signal.
3. The low frequency drive control circuit of claim 1 , further comprising a high frequency signal generator for generating said high frequency signal.
4. The low frequency drive control circuit of claim 1 , wherein said low frequency signal comprises a signal frequency of less than or equal to approximately 500 Hz.
5. The low frequency drive control circuit of claim 1 , wherein said high frequency signal comprises a signal frequency of approximately 20 kHz.
6. The low frequency drive control circuit of claim 1 , wherein said pulse width modulated output of said low frequency drive control circuit is provided to a switching circuit configured to generate said low frequency load current.
7. The low frequency drive control circuit of claim wherein said inductive load comprises a DC brushed motor.
8. A low frequency driver integrated circuit (IC) comprising:
a switching circuit of said low frequency driver IC coupled to a low frequency drive control circuit of said low frequency driver IC;
said low frequency drive control circuit configured for use with an inductive load and comprising:
a comparator configured to receive a high frequency signal at a first input and a low frequency signal for modulating said high frequency signal at a second input;
said comparator further configured to provide a pulse width modulated output of said low frequency drive control circuit to said switching circuit for use in generating a low frequency load current in said inductive load.
9. The low frequency driver IC of claim 8 , further comprising a low frequency signal generator for generating said low frequency signal.
10. The low frequency driver IC of claim 8 , further comprising a high frequency signal generator for generating said high frequency signal.
11. The low frequency driver IC of claim 8 , wherein said low frequency signal comprises a signal frequency of less than or equal to approximately 500 Hz.
12. The low frequency driver IC of claim 8 , wherein said high frequency signal comprises a signal frequency of approximately 20 kHz.
13. The low frequency driver IC of claim 8 , wherein said inductive load comprises a DC brushed motor.
14. A method for driving an inductive load at low frequency, said method comprising:
receiving a high frequency signal;
receiving a low frequency signal;
modulating said high frequency signal using said low frequency signal to produce a pulse width modulated output for use in generating a low frequency load current in said inductive load;
wherein said pulse width modulated output is a signal of low frequency pulses, each of said low frequency pulses including a plurality of high frequency signal variations.
15. The method of claim 14 , further comprising generating at least one of said low frequency signal and said high frequency signal.
16. The method of claim 14 , wherein said low frequency signal comprises a signal frequency of less than or equal to approximately 500 Hz.
17. The method of claim 14 , wherein said high frequency signal comprises a signal frequency of approximately 20 kHz.
18. The method of claim 14 , further comprising providing said pulse width modulated output to a switching circuit configured to generate said low frequency load current.
19. The method of claim 14 , wherein said inductive load comprises a DC brushed motor.