CN1848663A

CN1848663A - Brushless direct current motor drive circuit with modulation speed control

Info

Publication number: CN1848663A
Application number: CNA2006100726042A
Authority: CN
Inventors: 彼复·N·伍德
Original assignee: International Rectifier Corp USA
Current assignee: Infineon science and technology Americas
Priority date: 2005-04-05
Filing date: 2006-04-05
Publication date: 2006-10-18
Anticipated expiration: 2026-04-05
Also published as: CN100456622C

Abstract

Disclosed is a variable speed brushless direct current (BLDC) motor drive circuit. The circuit includes a plurality of high-side and low-side controlled switches coupled in a three-phase bridge configuration for commutating a BLDC motor, each phase of the bridge being connected to a corresponding phase of the motor, a controller for providing a drive signal to drive each of the high-side and low-side switches, and a speed control loop for controlling the motor by PWM of a DC bus voltage to achieve a constant motor speed. The speed control loop includes a pulse circuit receiving the drive signals provided from the controller for controlling the high-side switches and for providing a pulse signal that is related to a desired motor speed, a plurality of high-side drivers for driving the high-side switches, each high-side switch being coupled to a respective high-side driver, and a plurality of gating circuits each receiving the pulse signal from the pulse circuit and a drive signal for a respective high-side controller from the controller for generating a pulse width modulation (PWM) control signal having a pulse duration determined by said pulse signal from said pulse circuit to thereby drive each of the high-side drivers to modulate their corresponding high-side switches.

Description

The brushless direct current motor drive circuit of variable-ratio

The cross reference of related application

The application is based on the U.S. Provisional Application of submitting on April 5th, 2005, be entitled as " brshless DC motor that carries out the no transducer (sensorless) of pulse-width modulation speed control with electric machine frequency drives " the 60/668th, No. 897, and requiring its priority, its full content is incorporated this paper by reference into.

Technical field

The present invention relates to the motor-driven of brshless DC motor (BLDC), relate in particular to switch consume is minimized.

Background technology

Usually, use two kinds of distinct drivings (six step trapezoidal drivings (six-steptrapezoidal drive) and PWM drive) to drive heterogeneous BLDC motor.When using six to go on foot trapezoidal driving, carry out the speed adjustment by utilizing pre-regulator control direct current (DC) supply power voltage with high-frequency operation.When using PWM to drive, exchange (AC) output by the control volt-second and carry out the speed adjustment.That is to say, with high frequency the DC supply power voltage is carried out PWM and obtain above-mentioned speed adjustment.

Approach by commerce can obtain several six brushless drivings of step.The representative of these drivings is the TDA5142T integrated circuits (IC) 10 from Philips semiconductor maker (Philips Semiconductors), shown in the BLDC motor-drive circuit among Fig. 1.These IC 10 directly drive the power insulated gate bipolar transistor (IGBT) 14 that is connected with BLDC motor 12.

Two kinds of drivings, promptly six the step trapezoidal drivings and PWM drive, all needing can be with the power IGBT of high-frequency operation, so these two kinds of drivings all have significant switch efficiency consume.

Therefore, one object of the present invention is, a kind of three-phase PWM BLDC motor-drive circuit is provided, and can minimize IGBT or with the transistorized switch efficiency consume of the other types of high frequency operation.

Summary of the invention

BLDC drive circuit of the present invention has made up the best features of six trapezoidal drivings of step and PWM driving.Therefore, the feature of BLDC drive circuit of the present invention comprises the low-down switch conduction consume of (a) six step driver, and the PWM that (b) need not the AC output of high-frequency I GBT switch.These features make BLDC drive circuit of the present invention to use to have the standard speed IGBT that low conduction consume and low switch efficient are consumed when moving with electric machine frequency.In addition, the feasible total driving maximizing efficiency that produces of BLDC drive circuit of the present invention.

The commutation control of no transducer moved by zero the intersecting of detecting the back electromotive force (EMF) in the dead motor windings.These conditions generate the commutator pulse of the commutation that is used to optimize motor.In the middle of the process that starts, when not generating back-EMF, drive output and come timing, till producing back-EMF by frequency oblique ascension (ramp-up).

Except directly driving IGBT, BLDC drive circuit output trigger delay of the present invention makes each commutation constantly conduction time minimizing of IGBT at motor.By reducing the ON time of IGBT, the BLDC drive circuit has effectively reduced volt-second output, controls motor speed with this.

Volt-second control can be carried out in open cycle system, and in this open cycle system, motor speed is controlled by the analog control voltage source.As a kind of selection, volt-second control can be carried out in closed-loop system, and in closed-loop system, motor speed is adjusted according to circuit and load variations.

The BLDC drive circuit of variable-ratio of the present invention comprises a plurality of flash and lower edge switch, for example, be coupling in configuration and be used for making the igbt (IGBT) of the three-phase bridge line structure of BLDC motor commutation, each in the described bridge circuit is connected to the corresponding phase of motor.This circuit also comprises controller, and each that is used to flash and low limit IGBT provides drive signal, and described signal provided according to detected intersecting corresponding to the back electromotive force (EMF) zero with the output of corresponding each bridge circuit phase place of dead motor windings.

In addition, described circuit comprises speed control loop, is used for controlling motor by the pulse-width modulation (PWM) of DC bus voltage, to obtain constant motor speed.Speed control loop comprises impulse circuit, for example, dual monostable multi-frequency generator, being used to receive slave controller provides to the rising edge of the signal of flash IGBT; A plurality of high side drivers, be used to control flash IGBT, among described a plurality of flash IGBT each is coupled to high side drivers separately, and a plurality of gating circuits, it is from multi-frequency generator received pulse signal, and slave controller receives the signal be used for flash IGBT, and provides pwm signal for each (their corresponding flash IGBT are commutated) in the high side drivers.

After the description below carrying out of other features of the present invention and beneficial effect, will become apparent with reference to corresponding accompanying drawing.

Description of drawings

Fig. 1 is the schematic circuit diagram of the BLDC motor-drive circuit of employing TDA5142T IC of the prior art;

Fig. 2 is the schematic circuit diagram of BLDC motor-drive circuit of the present invention;

Fig. 3 A, 3B and 3C show respectively respectively at the Vce of the low limit IGBT of Vge, phase place A of minimum, medium and the low limit IGBT of phase place A when highly modulating and the waveform (6 step waveform) of motor phase A electric current;

Fig. 4 A and 4B are the figure that shows the PWM voltage and current waveform of the 5KHz microprocessor control that is used for 60 watts and 300 watt unit respectively;

Fig. 5 A is the figure that expression IGBT conduction loss is compared with the value of input power in the use table 1;

Fig. 5 B is the figure of expression efficient as the function of motor speed shown in the table 2 and input power;

Fig. 5 C is used for the figure that total IGBT loss of the 5KHz microprocessor control of prior art (Fig. 1) and electric machine frequency PWM according to the present invention is compared with input power.

Embodiment

Fig. 1 is illustrated in 300 watts of brushless direct-currents of typical three-phase (BLDC) the motor-driven integrated circuits (IC) 10 that use in the various application (comprising refrigeration).Microprocessor or digital signal processor (DSP) can be used to the output signal of the

1,2,4,5,23 of BLDC motor-driven

IC

10 and 24 is carried out pulse-width modulation (PWM).These pwm signals are used for driving power igbt (IGBT) 14, and IGBT 14 is provided for starting and moving the power of motor 12.Making the minimum required frequency of wave distortion and making compromise selection between the minimum required frequency of electromagnetic interference/radio frequency interference (EMI/RFI) of generation be used for the PWM frequency of this three phase BLDC motor-driven IC 10, be generally 4KHz to certain frequency between the 16KHz.

On the other hand, six steps drove to be generally 40 frequencies that arrive in the 300Hz scope and move motors, and controlled the adjustment of realization speed by direct current (DC) bus voltage that needs additional metal oxide semiconductor door switch.

Fig. 2 shows BLDC circuit for controlling motor 20 of the present invention.Control circuit 20 combines the optkmal characteristics of three-phase PWM BLDC motor-driven (as shown in Figure 1) and the driving of six steps.Control circuit 20 of the present invention is six steps drivings of carrying out PWM with electric machine frequency, therefore, need not to use microcontroller just can almost eliminate the switch power loss of IGBT, and makes the gross efficiency maximum of three phase BLDC motor driving controling circuit 20.

The present invention uses the BLDC motor-driven IC 10 of 15 volts of three-phases being designed to drive low pressure metal oxide semiconductor field effect transistor (MOSFET) or IGBT.For example, can use the above Philips TDA 5142T that describes with reference to Fig. 1 as BLDC motor-driven IC 10.The

1,5 and 23 of IC 10 is provided for driving three low limit N channel device A _L, B _LAnd C _LOutput signal.And the

2,4 and 24 of IC 10 is provided for driving three flash P-channel device A _H, B _HAnd C _HOutput signal.Low limit and flash device A, B and C (for example, the IGBT of the diode IRG4BC20SD with ultrafast soft recovery of Int Rectifier Corp) are coupled in the three-phase bridge line structure 22.

BLDC motor-driven IC 10 provides initial rotor location, and provides and quicken control, is used to be enabled in the BLDC motor (not shown) that phase place  A,  B and  C are connected to three-phase bridge circuit 22.Then, the speed control loop that the DC bus voltage is modulated is controlled motor, to obtain constant speed.Select to start oblique ascension dfreq/dt by external capacitive, produce back-EMF up to motor, back-EMF is detected at the

comparator input pin

19,20 and 21 that IC 10 corresponds respectively to phase place A, B and C then, and is used for making motor to commutate best.

The commutation number of times is to be intersected to determine by zero of the back-EMF of unperturbed motor windings.Normally in service, one of them of three-phase  A,  B and  C is connected to positive bus, and another is connected to negative bus, and third phase is to can be used to detect zero open circuit that intersects.

As mentioned above, directly drive the 600V IGBT A on low limit from three low limit output signals of

1,5 and 23 _L, B _LAnd C _LThree flash output signals from

2,4 and 24 are handled in corresponding two

input NOR gate

28A, 28B or 28C.The output of NOR gate is delivered to three corresponding high side drivers 26A, 26B and 26C (for example, the IR2117 IC of Int Rectifier Corp).

Second input of NOR

gate

28A, 28B or 28C is provided by dual one-shot multivibrator IC30 (for example, the CD4538IC of Fairchild Semiconductor (Fairchild Semiconductor Corporation)).The operation of IC 30 is by triggering from the rising edge of each in three flash signals of the

2,4 of BLDC motor-driven IC 10 and 24.The timing circuit of IC 30 is controlled by outside dc voltage and timing capacitor.The output pulse of IC 30 (with the frequency of three times of electric machine frequencies) provides second input as

NOR gate

28A, 28B or 28C.NOR gate produces required PWM input signal, and these signals are by high side drivers 26A, 26B and 26C and to three flash IGBTA _H, B _HAnd C _HModulate.Then, the PWM input signal is by the pulse daley from impulse circuit 30, thereby carries out pulse-width modulation to providing to the signal of the grid of flash switch with electric machine frequency.

Fig. 3 A, 3B and 3C represent to be used for to control the waveform of the PWM of power of motor.The waveform of phase voltage and phase current is in lowest modulation (high power), medium modulation and almost maximum modulation (that is minimum power input) time obtains.In Fig. 3 A, 3B and 3C, the Vge voltage of the low limit IGBT of the phase place A when curve Tr1 is illustrated in 20V/div; The Vce voltage of the low limit IGBT of phase place A when curve Tr2 is illustrated in 50V/div; And the motor phase A electric current of curve Tr3 when being illustrated in 2A/div.

Fig. 3 C represents to have 56 watts of maximum modulation, the 6 step waveforms of 50Hz, 3000RPM.Fig. 3 B represents to have 160 watts of medium modulation, the 6 step waveforms of 50Hz, 3000RPM.At last, Fig. 3 A represents to have highly 300 watts of modulation, the 6 step waveforms of 50Hz, 3000RPM.Fig. 3 A, 3B and 3C have been shown clearly in progressive (progressive) PWM electric machine frequency modulation in order to the control power of motor.

Get back to Fig. 2, the electric current of each motor windings of flowing through is via two conducting phase A, B being in the different operation phase in the three-phase bridge circuit or the instantaneous acquisition of C, and third phase is to be used for the open circuit of no-voltage joining of detected phase commutation.Three low limit IGBT A _L, B _LAnd C _LBe driven to normal 120 ° of angles of flow, and phase current is only at corresponding flash IGBT (that is A, _H, B _HAnd C _H) could flow during conducting, and this corresponding flash IGBT is modulated by the pulsewidth that reduces just, is generally 45 ° to 105 ° of 3000RPM, and hour increases pro rata in speed.

In speed very hour, this restriction may become excessive torque pulsation (torqueripple).But for not needing the very little compressor load of speed, this restriction can not cause problem.Typical refrigerant compressor/compressor of air conditioner moves with 3: 1 speed ratio, for example, is 50 to 150Hz or 1000 to 3000RPM for 6-pole motor.

For relatively, Fig. 4 A shows 60 watts, the PWM voltage and current waveform of 5KHz, microprocessor control, and Fig. 4 B shows 300 watts, the PWM voltage and current waveform of 5KHz, microprocessor control.

Circuit 20 is carried out test, so that the present invention is assessed.As mentioned above, in these tests, be IGBT 22 supply power by DC power supply 32, by the auxiliary power of second source 34 supply 15V and 9mA (0.135W).BLDC motor (not shown) is connected to phase  A,  B and  C via digital polyphase wattmeter (for example, Yokogawa WT1600).Motor is loaded by the DC generator of independent drive.Field current to this DC generator is regulated, being controlled to be 56W from the power of IGBT to 300W.

At first test period, the frequency dimension of BLDC motor be held in 100Hz (4 utmost points, 3000RPM).Result in the above-mentioned test shown in the table 1 has shown the variation of efficient with load current.These results have further represented under the situation very little and constant in switching loss, typical IGBT conduction loss.

Table 1

Electric machine frequency	The DC bus voltage	The DC input power	The AC power of motor	Total IGBT power loss	Efficient
Electric machine frequency	The DC bus voltage	The DC input power	The AC power of motor	Total IGBT power loss	Efficient	99.97Hz	122.32V	57W	55.8W	1.24W	97.83％
100.16	122.30	63	61.3	1.46	97.7	99.97Hz	122.32V	57W	55.8W	1.24W	97.83％
100.16	122.30	63	61.3	1.46	97.7	100.09	122.19	82	80.7	1.78	97.8
100.09	122.06	103	100.8	2.31	97.8	100.09	122.19	82	80.7	1.78	97.8
100.09	122.06	103	100.8	2.31	97.8	99.83	122.02	120	117.1	2.75	97.7
100.30	121.99	140	136.3	3.19	97.7	99.83	122.02	120	117.1	2.75	97.7
100.30	121.99	140	136.3	3.19	97.7	100.12	121.94	161	157.2	3.47	97.8
100.17	121.9	179	175.0	3.83	97.9	100.12	121.94	161	157.2	3.47	97.8
100.17	121.9	179	175.0	3.83	97.9	100.74	121.85	200	196.0	4.43	97.8
99.56	121.17	220	215.4	4.90	97.8	100.74	121.85	200	196.0	4.43	97.8
99.56	121.17	220	215.4	4.90	97.8	100.35	121.76	245	239.7	5.71	97.7
100.46	121.74	259	253.0	6.10	97.7	100.35	121.76	245	239.7	5.71	97.7
100.46	121.74	259	253.0	6.10	97.7	100.26	121.45	307	300.4	6.53	97.9

Fig. 5 A shows the figure as the IGBT conduction switch loss value of the function of corresponding D C input power value (being recorded in the table 1 equally) that is recorded in the table 1.It is quite little and constant the figure shows represented IGBT conduction loss.Also shown is in the gamut of 55 to 307 watts DC power input, the gross efficiency of circuit 20 is maintained constant 97.8% substantially.

Table 2 shows the result of another test, and wherein, motor load and motor speed are proportional, and the field excitation of DC generator loading remains constant.Therefore, torque is directly proportional with motor D C input power, and is inversely proportional to the revolution (RPM) of per minute.This test simulation have an actual compressor operation in the air-conditioning system of about 2: 1 input power ranges.

Table 2

Electric machine frequency	The DC bus voltage	The DC input power	The AC power of motor	Total IGBT power loss	Efficient
Electric machine frequency	The DC bus voltage	The DC input power	The AC power of motor	Total IGBT power loss	Efficient	52.93Hz	85.83V	116W	111.8W	4.37W	96.24％
63.19	92.62	151	145.7	5.02	96.67	52.93Hz	85.83V	116W	111.8W	4.37W	96.24％
63.19	92.62	151	145.7	5.02	96.67	77.32	111.20	206	200.1	5.90	97.14
87.73	120.9	251	244.8	6.52	97.41	77.32	111.20	206	200.1	5.90	97.14
87.73	120.9	251	244.8	6.52	97.41	99.40	121.64	302	294.9	7.07	97.66

Fig. 5 B show the expression gross efficiency of IGBT or 52.93Hz (1588RPM) to the value (in table 2, listing) of the motor speed of 99.4Hz (2982RPM) as the figure of 116W to the function of the DC input power (being recorded in the table 2 equally) of 302W.

In the 3rd test, the BLDC drive circuit 10 (as shown in Figure 1) that 300W, 5KHz, microcontroller drive is carried out test, as with the benchmark of above-mentioned two assessments.The 3rd the test condition with the test of circuit 20 is mated very much.Under the condition of the DC bus voltage of the speed of 100Hz (3000RPM), 121VDC, use identical no transducer BLDC motor and IGBT.The result of this test lists in table 3.

Table 3

Electric machine frequency	The DC bus voltage	The DC input power	The AC power of motor	Total IGBT power loss	Efficient
Electric machine frequency	The DC bus voltage	The DC input power	The AC power of motor	Total IGBT power loss	Efficient	100.1Hz	121.86V	60W	57.3W	2.76W	95.41％
100.5	121.83	100	95.8	3.91	96.08	100.1Hz	121.86V	60W	57.3W	2.76W	95.41％
100.5	121.83	100	95.8	3.91	96.08	100.45	121.80	140	135.0	5.13	96.34
100.19	121.79	180	173.2	6.44	96.42	100.45	121.80	140	135.0	5.13	96.34
100.19	121.79	180	173.2	6.44	96.42	100.4	121.57	220	212.1	7.78	96.46
100.37	121.45	260	250.6	9.39	96.39	100.4	121.57	220	212.1	7.78	96.46
100.37	121.45	260	250.6	9.39	96.39	100.14	121.42	300	288.7	10.90	96.36

The premium properties of electric machine frequency pwm circuit of the present invention can be from be recorded in table 1 the result and be recorded in the comparison between the result in the table 3 and clearly find out.Creative circuit 20 of the present invention reduces the conduction loss of IGBT, thereby makes that the efficient at 60 watt-hours is 97.7% (contrast 95.4%), and is 97.9% (contrasts 96.36%) in the efficient of 300 watt-hours.In addition, the present invention does not need to use radiator when using IGBT (for example, the TO-220 100V power MOSFET of Int Rectifier Corp).In three-phase module,, therefore still need to use radiator because package dimension is less and the power density of generation is bigger.

Fig. 5 C represented in Fig. 1, use microprocessor to produce the PWM output signal with the reference circuit (having shown higher IGBT loss) control IGBT, that in the 3rd test, use and the difference of the switch conduction loss between the electric machine frequency pwm circuit 20 of the present invention.

Though invention has been described with reference to specific embodiment, to those skilled in the art, many other variation and revision and uses are conspicuous.Therefore, the present invention should not be subjected to the concrete disclosed restriction of this paper.

Claims

1. the brushless direct-current of a variable-ratio (BLDC) motor-drive circuit comprises:

A plurality of flash controlled switchs and low limit controlled switch are coupling in the three-phase bridge line structure that is used for making the BLDC motor commutation, and each in the described bridge circuit is connected to the corresponding phase of described motor;

Controller is used to provide drive signal, to drive each in described flash switch and the lower edge switch;

Speed control loop is used for controlling described motor by the PWM of DC bus voltage, and to obtain constant motor speed, described speed control loop comprises:

The described drive signal that is provided by described controller is provided impulse circuit, is used to control described flash switch, and is used to the pulse signal that provides relevant with the motor speed of expecting to obtain;

A plurality of high side drivers are used to drive described flash switch, and each in described a plurality of flash switches is coupled to high side drivers separately; And

A plurality of gating circuits, its each from described impulse circuit received pulse signal, and the drive signal that is used for each flash controller from described controller reception, be used for the production burst duration by pulse-width modulation (PWM) control signal of determining from the described pulse signal of described impulse circuit, drive each described high side drivers with this and modulate their corresponding separately flash switches.

2. circuit as claimed in claim 1, wherein, described switch is igbt (IGBT).

3. circuit as claimed in claim 2, wherein, described low limit IGBT is the N channel device, described flash IGBT is a P-channel device.

4. circuit as claimed in claim 1, wherein, described controller further is provided for starting the initial rotor location of described motor and quickening control.

5. circuit as claimed in claim 4, wherein, provide described signal in response to the detection that back electromotive force (EMF) zero is intersected, zero of described back electromotive force gives the output of each bridge circuit phase place corresponding mutually, and the output of described each bridge circuit phase place is corresponding with the dead motor windings.

6. circuit as claimed in claim 5, wherein, described controller is a plurality of signals of each Phase Receiver from described three-phase bridge circuit further, and the back-EMF zero that described signal is used to detect the dead winding of described motor intersects, and is used to provide the commutation number of times.

7. circuit as claimed in claim 6, wherein, before described motor generated back-EMF, external capacitive was selected the startup oblique ascension dfreq/dt of described controller.

8. circuit as claimed in claim 5, wherein, between the starting period, when not having the back-EMF that generates, driver output comes timing by the frequency oblique ascension, till producing back-EMF.

9. circuit as claimed in claim 1, wherein, described controller is integrated circuit (IC).

10. circuit as claimed in claim 9, wherein, described IC is three-phase, 15 volts, BLDC motor-driven IC.

11. circuit as claimed in claim 1, wherein, the operation of described impulse circuit is that the rising edge by the described signal from described controller to described flash switch triggers.

12. circuit as claimed in claim 11, wherein, described impulse circuit is exported described pulse signal with the frequency of three times of electric machine frequencies.

13. circuit as claimed in claim 12, wherein, the timing circuit of described impulse circuit is controlled by outside dc voltage and timing capacitor.

14. circuit as claimed in claim 1, wherein, in each commutation moment of described motor, the time of described pwm signal by-pass cock conducting electric current.

15. circuit as claimed in claim 14, wherein, the adjusting of described switch conduction time is regulated the volt-second output of controlling described motor speed.

16. circuit as claimed in claim 14, wherein, described volt-second is adjusted in the open cycle system to be carried out, and in described open cycle system, described motor speed is controlled by the analog control voltage source.

17. circuit as claimed in claim 14, wherein, described volt-second is adjusted in the closed-loop system to be carried out, and in described closed-loop system, described motor speed is regulated according to circuit and load variations.

18. circuit as claimed in claim 1, wherein, the conduction loss of described switch is minimized, and the gross efficiency of described motor is maximized.

19. circuit as claimed in claim 1, its running refrigerating compressor/compressor of air conditioner, described compressor moves with about 3: 1 speed ratio for six step motors.

20. circuit as claimed in claim 1, wherein, described impulse circuit is dual one-shot multivibrator.

21. circuit as claimed in claim 1, wherein, described gating circuit comprises two input NOR gate.

22. one kind is used for the motor-drive circuit at the BLDC of variable-ratio, uses the pulse-width modulation (PWM) of DC bus voltage to control brushless direct-current (BLDC) motor, to obtain the method for constant motor speed, described method comprises:

Detect zero of back electromotive force (EMF) and intersect, zero of described back electromotive force gives the output of each bridge circuit phase place corresponding mutually, and the output of described each bridge circuit phase place is corresponding with the dead winding of described motor;

For in a plurality of flash switches and the lower edge switch each provides control signal, described flash switch and lower edge switch are coupling in the three-phase bridge line structure that is used for making described motor commutation, and described lower edge switch directly receives described signal; And

For each flash switch:

Carry out the gate operation to described signal and by the pulse signal that the impulse circuit that receives described control signal provides, with generation be used for each flash switch, the pulse duration is by the control pwm signal of determining from the described pulse signal of described impulse circuit; And

Drive described flash switch with described pwm signal,

Wherein, in each commutation moment of described motor, the time of described pwm signal by-pass cock conducting electric current.