CN104821759A - Brushless direct current motor starting control method with no position sensor for fuel pump - Google Patents

Abstract

The invention relates to a brushless direct current motor starting control method with no position sensor for a fuel pump. The method comprises the steps: dividing a DC bus voltage fluctuation range of motor operation into sections; calculating a starting duty ratio compensation value delta D0 and a switching duty ratio compensation value delta D1 under the condition of a rated working voltage when a testing motor changes with temperature; calculating a starting duty ratio compensation value delta D0x and a switching duty ratio compensation value delta D1x; determining the starting parameters of the motor according to a temperature signal T DEG C: a starting duty ratio compensation value delta D'0x and a switching duty ratio compensation value delta D'1x; and carrying out three-section starting control of the motor. The method just needs to acquire two parameters: a DC bus voltage and environmental temperature, so the method is easier to achieve. In addition, the method just needs two steps to complete the process of self-regulation of starting parameters, and the operation is linear operation. Therefore, the method can be conveniently used in actual projects.

Description

Fuel pump brushless DC motor without position sensor method for starting-controlling

Technical field

The starting that the invention belongs to motor controls, and is specifically related to a kind of fuel pump brushless DC motor without position sensor method for starting-controlling.

Background technology

Brshless DC motor forms primarily of motor body, electronics commutation circuit and rotor-position sensor three parts.Position transducer is as the highest parts of brshless DC motor failure rate, and it exists the reliability and the cost and the volume that add motor that reduce brshless DC motor.Therefore, the brshless DC motor of position-sensor-free and control technology thereof become the focus of recent researches.Although the control technology of brushless DC motor without position sensor comparative maturity, but position sensor control can not be substituted.The starting of brushless DC motor without position sensor is a difficult problem for its development of puzzlement always, that to be the most ripe be also three steps start method is the most frequently used without position method for starting-controlling, but need to design acceleration curve targetedly to control system, just can not ensure the reliable starting of motor when busbar voltage or load change.

Fuel pump load is the desired load of brushless DC motor without position sensor, but must change in busbar voltage, can reliably start under the mal-condition such as variations in temperature due to its special operating environment requirements drive motors.Busbar voltage change can affect the electromagnetic torque in motor starting process, and during variations in temperature, fuel-viscosity variation can change and then cause the change of electric motor load torque, and above situation all can cause the acceleration curve of motor to change, and affects motor normal starting.Therefore, the proposition of the reliable method for starting-controlling of brushless DC motor without position sensor, contributes to promoting the application of brushless DC motor without position sensor in the fields such as Aero-Space, has important practical significance.

Summary of the invention

The technical problem solved

In order to avoid the deficiencies in the prior art part, the present invention proposes a kind of fuel pump brushless DC motor without position sensor method for starting-controlling, can realize the reliable starting of motor when busbar voltage and load torque change.Significantly reduce the failure rate of electric motor starting failure, reduce aircraft " possibility of flame-out in flight ", to the application of brushless DC motor without position sensor in aerospace field, there is positive impetus.

Technical scheme

A kind of fuel pump brushless DC motor without position sensor method for starting-controlling, is characterized in that step is as follows:

Step 1: the DC bus-bar voltage fluctuation range of machine operation is divided into 5 ~ 8 intervals, determines according to formula (1) and (2) the starting duty ratio D controlling electric motor starting in different voltage range _0xwith switching duty cycle D _1x:

$D_{0x}=\frac{U_0}{U_x}---\left(1\right)$

$D_{1x}=\frac{U_1}{U_x}---\left(2\right)$

Wherein: U ₀represent starting voltage, U ₁represent and be synchronized to self synchronous switched voltage from outward, U _xrepresent the magnitude of voltage of different voltage ranges, x=1,2,3...;

Step 2: in rated operational voltage situation, starting duty ratio offset Δ D when testing of electric motors varies with temperature ₀with switching duty cycle offset Δ D ₁, wherein:

$\left\{\begin{array}{c}\mathrm{\Δ}{D}_0=(0.2~0.5)\·D_0\\ D_0=U_0/U_d\end{array}---\left(3\right)\right.$

$\left\{\begin{array}{c}\mathrm{\Δ}{D}_1=(0.2~0.5)\·D_1\\ D_1=U_1/U_d\end{array}---\left(4\right)\right.$

Wherein: D ₀represent duty ratio when starting under rated operational voltage, D ₁represent duty ratio when switching under rated operational voltage, U _drepresent busbar voltage;

Step 3: calculate and start duty ratio offset Δ D _0xwith switching duty cycle offset Δ D _1x:

ΔD _0x＝ΔD ₀·U _d/U _x(5)

ΔD _1x＝ΔD ₁·U _d/U _x(6)

Step 4: according to the value of temperature signal T DEG C, determine the start-up parameters of motor: start duty ratio D' _0xwith switching duty cycle D ' _1x,

$D_{0x}^{\&prime;}=\left\{\begin{array}{cc}{D}_{0x}+\mathrm{\&Delta;}{D}_{0x}& (T<-25)\\ D_{0x}& (T\&GreaterEqual;-25)\end{array}---\left(7\right)\right.$

$D_{1x}^{\&prime;}=\left\{\begin{array}{cc}{D}_{1x}+\mathrm{\&Delta;}{D}_{1x}& (T<-25)\\ D_{1x}& (T\&GreaterEqual;-25)\end{array}---\left(8\right)\right.$

Step 5: according to the start-up parameters D' of motor _0xwith D ' _1x, three steps start control is carried out to motor.

Beneficial effect

A kind of fuel pump brushless DC motor without position sensor method for starting-controlling that the present invention proposes, compared with prior art has the following advantages:

(1) fuel pump starts the method for starting-controlling usually using syllogic with brushless DC motor without position sensor, the motor acceleration curve adaptability of the method design is bad, once motor load changes or the failure that fluctuation all probably causes electric motor starting occurs DC bus-bar voltage.And the method for starting-controlling that the present invention proposes, take into account the harsh conditions such as busbar voltage fluctuation and load torque change probably occurred in the fuel pump course of work just, propose corresponding solution targetedly, thus ensure that the reliability that motor starts in the presence of a harsh environment.Contribute to promoting the application of Sensorless Control Technique in China's Aerospace Products, reduce and external gap in this technical field.

(2) due to conventional brushless DC motor without position sensor control system, itself generally all possesses DC bus-bar voltage and ambient temperature detection circuit, and therefore this method does not need to carry out extra circuit design.

(3) because this method only needs to obtain DC bus-bar voltage and ambient temperature two parameters, therefore realize also fairly simple, in addition, the method carries out the self-adjusting process of start-up parameters only needs two steps, and be linear operation, therefore facilitate and use in engineering reality.

Accompanying drawing explanation

Fig. 1: brshless DC motor band fuel pump load step-up ascending frequency curve.

Fig. 2: start control flow chart.

Fig. 3: busbar voltage and temperature collection circuit;

(a) busbar voltage testing circuit schematic diagram

(b) temperature sensing circuit schematic diagram

Fig. 4: frequency ascending curve and duty ratio ascending curve;

(a) frequency ascending curve

(b) duty ratio ascending curve

Fig. 5: the test waveform of busbar voltage is 24V ambient temperature when being-30 DEG C loaded starting.

Embodiment

Now in conjunction with the embodiments, the invention will be further described for accompanying drawing:

The inventive method can realize the reliable starting of motor when busbar voltage and load torque change, significantly reduce the failure rate of electric motor starting failure, reduce aircraft " possibility of flame-out in flight ".

Under normal circumstances, as shown in Figure 1, commutation frequency during starting is f to the acceleration curve of electric motor starting ₀, switch time commutation frequency be f ₁, starting voltage is U ₀, switched voltage is U ₁, switching time is t ₁.The method is by detecting the busbar voltage of motor and ambient temperature and judging, thus the start-up parameters of adjustment motor automatically, to adapt to the start request of motor in different busbar voltage and different temperatures situation.

Specific embodiment, with a 260W fuel pump brushless DC motor without position sensor control system for object carries out verification experimental verification, the rated operational voltage of this motor is 28V.

The busbar voltage of brushless DC motor without position sensor control system and temperature collection circuit, as shown in Figure 3, wherein OPA365 is voltage follower.According to supply power voltage and the PWM chopping frequency of system, select the value of divider resistance RV1, RV2 and CV1, make sampled voltage amplitude within 0 ~ 3V, and need the PWM copped wave of filtering busbar voltage medium-high frequency to disturb.Supply power voltage due to system is 28V, PWM chopping frequency is 25kHz, therefore selects divider resistance RV1=100k Ω, RV2=9.1k Ω; In order to the PWM copped wave interference in filtering busbar voltage, select CV1=0.022 μ F.

Under normal circumstances, in the acceleration curve of electric motor starting: commutation frequency f during starting ₀commutation frequency f when=10Hz, switching ₁=85Hz, starting voltage U ₀=1.4V, switched voltage U ₁=5.6V, switching time t ₁=0.5s.

The first step: the excursion of DC bus-bar voltage is 22V ~ 32V, is divided into 6 different intervals, is determined the starting duty ratio D of electric motor starting in different voltage range according to formula (1) and (2) _0xwith switching duty cycle D _1x.Its frequency ascending curve and duty ratio ascending curve are as shown in Figure 4.

Second step: in rated operational voltage situation, is determined by experiment motor temperature variant starting duty ratio offset and meets: Δ D ₀=0.3D ₀=0.3 × 1.4/28=0.015, switching duty cycle offset meets: Δ D ₁=0.3D ₁=0.3 × 5.6/28=0.06.

3rd step: suppose that current bus voltage value is 24V, starts duty ratio D according to determining between busbar voltage location _0xand start duty ratio offset Δ D _0x, switching duty cycle D _1xwith switching duty cycle offset Δ D _1xmeet respectively:

$\left\{\begin{array}{c}{D}_{0x}=U_0/U_x=1.4/24=0.058\\ \mathrm{\&Delta;}{D}_{0x}=\mathrm{\&Delta;}{D}_0\&CenterDot;U_d/U_x=0.015\&times;28/24=0.0175\end{array}---\left(9\right)\right.$

$\left\{\begin{array}{c}{D}_{1x}=U_1/U_x=5.6/24=0.23\\ \mathrm{\&Delta;}{D}_{1x}=\mathrm{\&Delta;}{D}_1\&CenterDot;U_d/U_x=0.06\&times;28/24=0.07\end{array}---\left(10\right)\right.$

4th step: suppose now ambient temperature signal T=-30 (DEG C), the starting duty ratio D' of motor _0xwith switching duty cycle D ' _1xfor:

$\left\{\begin{array}{c}{D}_{0x}^{\&prime;}=D_{0x}+\mathrm{\&Delta;}{D}_{0x}=0.058+0.0175=0.0775\\ D_{1x}^{\&prime;}=D_{1x}+\mathrm{\&Delta;}{D}_{1x}=0.23+0.07=0.30\end{array}\right.---\left(11\right)$

5th step: according to the start-up parameters (D' calculated _0xwith D ' _1x), carry out three steps start control according to control flow chart (Fig. 2) to motor in conjunction with the acceleration curve (Fig. 1) of motor, it starts experimental waveform as shown in Figure 5.

Claims (1)

1. a fuel pump brushless DC motor without position sensor method for starting-controlling, is characterized in that step is as follows:

Step 1: the DC bus-bar voltage fluctuation range of machine operation is divided into 5 ~ 8 intervals, determines according to formula (1) and (2) the starting duty ratio D controlling electric motor starting in different voltage range _0xwith switching duty cycle D _1x:

$D_{0x}=\frac{U_0}{U_x}---\left(1\right)$

$D_{1x}=\frac{U_1}{U_x}---\left(2\right)$

Wherein: U ₀represent starting voltage, U ₁represent and be synchronized to self synchronous switched voltage from outward, U _xrepresent the magnitude of voltage of different voltage ranges, x=1,2,3...;

Step 2: in rated operational voltage situation, starting duty ratio offset Δ D when testing of electric motors varies with temperature ₀with switching duty cycle offset Δ D ₁, wherein:

$\left\{\begin{array}{c}{\mathrm{\&Delta;D}}_0=(0.2~0.5)\&CenterDot;D_0\\ D_0=U_0/U_d\end{array}\right.---\left(3\right)$

$\left\{\begin{array}{c}{\mathrm{\&Delta;D}}_1=(0.2~0.5)\&CenterDot;D_1\\ D_1=U_1/U_d\end{array}\right.---\left(4\right)$

Wherein: D ₀represent duty ratio when starting under rated operational voltage, D ₁represent duty ratio when switching under rated operational voltage, U _drepresent busbar voltage;

Step 3: calculate and start duty ratio offset Δ D _0xwith switching duty cycle offset Δ D _1x:

ΔD _0x＝ΔD ₀·U _d/U _x(5)

ΔD _1x＝ΔD ₁·U _d/U _x(6)

Step 4: according to the value of temperature signal T DEG C, determine the start-up parameters of motor: start duty ratio D' _0xwith switching duty cycle D ' _1x,

$D_{0x}^{\&prime;}=\left\{\begin{array}{cc}{D}_{0x}+{\mathrm{\&Delta;D}}_{0x}& (T<-25)\\ D_{0x}& (T\&GreaterEqual;-25)\end{array}\right.---\left(7\right)$

$D_{1x}^{\&prime;}=\left\{\begin{array}{cc}{D}_{1x}+{\mathrm{\&Delta;D}}_{1x}& (T<-25)\\ D_{1x}& (T\&GreaterEqual;-25)\end{array}\right.---\left(8\right)$

Step 5: according to the start-up parameters D' of motor _0xwith D ' _1x, three steps start control is carried out to motor.