Sensed motor winding current adapting blanking period between max/min values

Patent metadata

Field	Value
Publication number	US-9397597-B2
Application number	US-201414257998-A
Country	US
Kind code	B2
Filing date	Apr 21, 2014
Priority date	Jul 29, 2013
Publication date	Jul 19, 2016
Grant date	Jul 19, 2016

Abstract

Stepper motor winding current regulation methods and apparatus adapt a maximum blanking period to generate an adapted blanking period that is proportional to a currently-selected current regulation set-point. Sensed winding current feedback is ignored at a current regulation controller during the adapted blanking period or during a minimum blanking period, whichever longer, to avoid attempting to track noise imposed upon a sensed winding current feedback signal at an initiation of rapid current changes di/dt. Doing so may decrease ripple in the motor winding current waveform and reduce zero-crossing distortion by decreasing overshoot of the current regulation set-point by the sensed winding current.

First claim

What is claimed is:

1. A process of establishing an adapted blanking period in a pulse width modulated cycle providing current through a motor winding to a set point level of motor winding current ITRIP, comprising:
(a) storing a minimum blanking period value in a minimum register and a maximum blanking period value in a maximum register;
(b) passing a motor winding current through the motor winding and parasitic tank circuitry coupled to the motor winding, the parasitic tank circuitry including a sensing resistor;
(c) sensing a motor winding current through the resistor;
(d) determining in controller circuitry the adapted blanking period based on the sensed motor winding current;
(e) limiting the adapted blanking period to be between the minimum blanking period value and the maximum blanking period value; and
(f) blanking the sensing of the motor winding current during the adapted blanking period.

2. The process of claim 1 in which the passing includes passing the motor winding current through a stepper motor winding.

3. The process of claim 1 in which the determining includes determining the adapted blanking period as a function of an absolute value of sensed motor winding current for a set point level of motor winding current ITRIP.

4. The process of claim 1 in which the sensing includes sensing a motor winding current within one of certain ranges and the determining includes determining a certain adapted blanking period based on the one sensed motor winding current range.

5. The process of claim 1 in which the blanking includes avoiding noise imposed on the sensed motor winding current through the resistor from a rapid change in current through the tank circuit.

6. The process of claim 1 including effecting at least one of a slow decay and a fast decay of motor winding current after the blanking period.

7. The process of claim 1 in which the passing includes controlling the passing with a pulse width modulation cycle controller, containing the minimum register and the maximum register, coupled to the sense resistor and coupled through a driver circuit and an H-bridge circuit to the motor winding.

8. A motor circuit comprising:
(a) a motor winding having a first lead and a second lead;
(b) an H-bridge circuit coupling a voltage source to the first lead and a ground source to the second lead, and having bridge control inputs;
(c) a parasitic tank circuit coupled between the second lead and the ground source, the parasitic tank circuit including a sense resistor;
(d) a driver circuit having bridge control outputs coupled to the bridge control inputs and having a driver control input;
(e) current sense circuitry having sense leads coupled to the sense resistor and having current sense outputs, one of the current sense outputs carrying a signal indicating the motor winding current through the resistor;
(f) a waveform converter having a converter output;
(g) comparator circuitry having a first input coupled to the one current sense output, a second input coupled to the converter output, and a comparator output; and
(h) a pulse width modulation controller having a driver control output coupled to the driver control input, and control inputs including a sense input coupled to the comparator output, the modulation controller including a blanking time adaptation controller having a minimum blanking period value register and a maximum blanking period value register, the adaptation controller blanking a sensing of the comparator input during an adapted blanking period determined between values contained in the minimum blanking period value register and the maximum blanking period value register based on the control inputs.

9. The circuit of claim 8 including a torque converter having an output summed with the output of the waveform converter and coupled to the second input of the comparator circuitry.

10. The circuit of claim 8 in which the comparator circuitry includes a set point comparator having one first input coupled to the one current sense output, one second input coupled to the converter output, and one comparator output.

11. The circuit of claim 8 in which the current sense circuitry has another current sense output carrying a signal indicating the motor winding current through the resistor, and the comparator circuitry includes:
a first comparator having a non-inverting input coupled to the one current sense output, an inverting input coupled to the converter output, and a crossing negative output coupled to the modulation controller; and
a second comparator having a non-inverting input coupled to the another current sense output, an inverting input coupled to the converter output, and a crossing positive output coupled to the modulation controller.

12. The circuit of claim 11 including a torque converter having an output summed with the output of the waveform converter and coupled to the inverting inputs of the first and second comparators.

Assignees

• Texas Instruments Inc

Inventors

• Qu Wenchao
• Jain Anuj
• Kehr Ryan Paul

Classifications

• H02P8/12 Primary

  Control or stabilisation of current · CPC title