CN107872184A - Optimal design of a switched reluctance motor controller - Google Patents

Abstract

The present invention relates to a kind of Optimization Design for switched reluctance motor controller, including orientation optimization to design, the design of closed loop Angle-domain imaging circuit and the design of Current cut control circuit.Benchmark is used as by the use of the saltus step of integrated signal, pass through an adjustable delay circuit, along with appropriate digital-to-analogue combinational circuit integrates out a three-phase control signal, this three-phase control signal can realize the regulation at shut-off angle by adjusting the delay time of delay circuit；A proportional and integral controller is added, to automatically adjust the discharge current of electric capacity, reaches the purpose of control turn-on angle.

Description

Optimal design of a switched reluctance motor controller

technical field

The invention relates to the control of switched reluctance motors, especially the design of the angle optimization circuit of the controller and the optimization design of the current chopper control circuit.

Background technique

Due to its unique physical structure, switched reluctance motors are simple and solid, easy to manufacture, suitable for high-speed work, good fault tolerance, strong overload capacity, high efficiency and specific power indicators, good charging performance for batteries, and many controllable parameters. At the same time, under the control of the microcomputer, it can be used as both a motor and a generator, and the control is flexible, so it is possible to combine the starter and generator of the car into one, simplifying the structure of the car , reduce cost, improve power and reliability. The switched reluctance starter generator for aircraft started in the late 1980s in foreign countries has entered the product test stage. The domestic research on switched reluctance generators began in the early 1990s, and began to focus on switched reluctance generators and aircraft starter generators. In addition, a large number of experiments have been done with 8031, 80C196 and other control chips, and the operating mechanism of the switched reluctance motor as a generator and the control method as a starter generator have been systematically described, and some optimal control strategies have been proposed. At present, the research on switched reluctance generators is still in the stage of laboratory research, and the focus of research is mostly on the control method.

Contents of the invention

The technical problem to be solved by the present invention is: in order to overcome the deficiency of high error rate in the existing controller, the present invention provides an optimized controller design. The technical solutions adopted by the present invention to solve the technical problems include:

(1) Angle optimization circuit design

There is always a jump signal every 15°, so the three-phase signals can be synthesized into a composite signal that jumps every 15°. Using a certain jump of the integrated signal as a reference, through an adjustable delay circuit, coupled with an appropriate digital-analog combination circuit, a three-phase control signal is synthesized, and the three-phase control signal can be adjusted by adjusting the delay of the delay circuit. Time to realize the adjustment of the cut-off angle.

(2) Design of closed-loop angle position control circuit

A PI regulator is added to automatically adjust the discharge current of the capacitor C2 to achieve the purpose of controlling the turn-on angle. Therefore, the transistor Q2 here works in the amplification region instead of the saturation region. U _f in the figure is the feedback value. If current regulation is required, the feedback value should be the bus current. If it is voltage regulation, it should be the bus voltage. U _r in the figure is the reference value of the control circuit, and the model of the entire PI regulator is shown in the following formula.

(3) Design of current chopping control circuit

Current chopping is a method of current protection, so even in the angle position control mode, a current chopping circuit is needed as a current protection. At the same time, because the essence of current chopping is to control the magnitude of the excitation phase current of the switched reluctance generator , and the magnitude of the phase current will be directly related to the magnitude of the output power.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Figure 1 is an optimization circuit for the turn-off angle.

Figure 2 is a timing diagram for optimizing the turn-off angle.

Figure 3 is the angle position control circuit.

Figure 4 is the timing sequence of angular position control.

Figure 5 is the current chopping control circuit.

Detailed ways

The present invention is described in further detail now in conjunction with accompanying drawing. These drawings are all simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner, so they only show the configurations related to the present invention.

The technical solutions adopted by the present invention to solve the technical problems include:

(1) Angle optimization circuit design

In the switched reluctance power generation system, the turn-off angle is relatively sensitive to the influence of the output power, and there is an optimal point, which basically does not change with the change of the speed, but the turn-on angle is different, and the change in the turn-on angle is quite large In the range of , it has a good linear relationship with the output power. Therefore, the turn-on angle is suitable as the control quantity of the angle position feedback control, and in order to ensure that the turn-off angle can be near the optimum point, it is necessary to optimize the turn-off angle in advance. Therefore, an optimized circuit for the turn-off angle is specially designed. The design idea of this circuit is as follows: there is always a jump signal every 15°, so the three-phase signals can be synthesized into a comprehensive signal that jumps every 15°. Using a certain jump of the integrated signal as a reference, through an adjustable delay circuit, coupled with an appropriate digital-analog combination circuit, a three-phase control signal is synthesized, and the three-phase control signal can be adjusted by adjusting the delay of the delay circuit. Time to realize the adjustment of the turn-off angle, the circuit design is shown in Figure 1.

When the integrated signal jumps up, there must first be a phase position signal jumping up. At the same time, the transistor Q1 used for current driving is saturated and turned on, and the +5V voltage quickly charges the capacitor C1 through the diode D2, and the capacitor C1 is charged to the LM339 At the moment before the reference voltage, 74LS373 is at high level, so the upper jump position signal of a certain phase can pass through 74LS373 smoothly and be reflected to the output terminal. When capacitor C1 is charged to the reference voltage, LM339 outputs low level, and 74LS373 latches state; when the integrated signal jumps down, there must be a down jump in the position signal of one phase. At this time, the capacitor is discharged through the resistor R6 and the diode D1. The discharge time can be changed by adjusting R6, so there is also a flip of the LM339 output. Delay, then the position signal of a certain phase has to be delayed to pass through 74LS373. Using this delay principle, and fully logically synthesizing and utilizing the position signals of each phase, a set of turn-off angles can be obtained. The specific time sequence of the adjusted three-phase switching signal is shown in Fig. 2 .

The falling edge of the position signal of each phase is the on position of the control signal of this phase, and the off position of the control signal can be adjusted by the potentiometer R6 within the range of △α, where △α≤15° (mechanical angle), so if it is reasonable By adjusting the relative position of the turntable and the position sensor, a reasonable opening angle position on the relative phase inductance curve can be obtained. Then, the off angle is optimized to obtain the optimal output power. On this basis, the opening angle Angular position feedback control for the control parameter.

(2) Design of closed-loop angle position control circuit

For the angle position control mode, the opening angle is generally controlled, and an angle position control circuit based on an analog PI regulator is also designed here. The design idea of this circuit is similar to the turn-off angle optimization circuit. The main difference is that firstly, the manual adjustment of the capacitor discharge current is changed to an automatic adjustment method. Secondly, the rising edge of the control signal should be adjusted here, that is, the turn-on angle position. The circuit design is shown in Figure 3.

A PI regulator is added to automatically adjust the discharge current of the capacitor C2 to achieve the purpose of controlling the turn-on angle. Therefore, the transistor Q2 here works in the amplification region instead of the saturation region. U _f in the figure is the feedback value. If current regulation is required, the feedback value should be the bus current. If it is voltage regulation, it should be the bus voltage. U _r in the figure is the reference value of the control circuit, and the model of the entire PI regulator is shown in the following formula.

For the PI regulator, the most important thing is the design of PI parameters, the design here follows the following principles:

(a) The feedback value is within a certain range near the steady-state value, so that the transistor Q2 can work at any point in the amplification area;

(b) Because the angle continuous adjustment range of the circuit is only 15° (mechanical angle), the adjustment intensity cannot be too large, but the response speed should be as fast as possible, which is also the usual requirement of the PI regulator.

It can be seen from Figure 4 that the range of the opening angle △α is continuously adjusted to a maximum of 15° (mechanical angle), that is, after adjusting the turntable according to the optimized off angle, the adjustment range of the opening angle is (θ _off -45°)～(θ _off -30°).

(3) Design of current chopping control circuit

Current chopping is a method of current protection, so even if it is an angle position control method, at the same time, because the essence of current chopping is to control the magnitude of the excitation phase current of the switched reluctance generator, and the magnitude of the phase current will directly affect the The size of the output power. Figure 5 shows the current chopping control circuit.

U _r is the reference input of the system, and U _f is the feedback quantity, which can also be the bus current or the bus voltage. The output of the PI regulator is isolated by a voltage follower and used as the reference input of the chopper circuit.

Claims (1)

1. A kind of 1. optimization design for switched reluctance motor controller, it is characterised in that：Including

   (1) include orientation optimization to design

   Always there is a skip signal every 15 °, therefore can be three-phase signal synthesis into the comprehensive letter every 15 ° of saltus steps once Number.By the use of some saltus step of integrated signal as benchmark, by an adjustable delay circuit, along with appropriate digital-to-analogue group Close circuit synthesis and go out a three-phase control signal, this three-phase control signal can be by adjusting the delay time of delay circuit come real Now turn off the regulation at angle.

   (2) design of closed loop Angle-domain imaging circuit

   A pi regulator is added, to automatically adjust the discharge current of electric capacity, reaches the purpose of control turn-on angle, control three Pole pipe is operated in amplification region, rather than saturation region.The model of pi regulator is shown below.U_fIt is value of feedback, U_rIt is then control electricity The a reference value on road.

   <mrow> <msub> <mi>U</mi> <mi>o</mi> </msub> <mo>=</mo> <msub> <mi>U</mi> <mi>r</mi> </msub> <mo>+</mo> <mrow> <mo>(</mo> <mfrac> <msub> <mi>R</mi> <mn>8</mn> </msub> <msub> <mi>R</mi> <mn>6</mn> </msub> </mfrac> <mo>+</mo> <mfrac> <mn>1</mn> <mrow> <msub> <mi>R</mi> <mn>6</mn> </msub> <msub> <mi>C</mi> <mn>1</mn> </msub> <mi>s</mi> </mrow> </mfrac> <mo>)</mo> </mrow> <mrow> <mo>(</mo> <msub> <mi>U</mi> <mi>r</mi> </msub> <mo>-</mo> <msub> <mi>U</mi> <mi>f</mi> </msub> <mo>)</mo> </mrow> </mrow>

   (3) design of Current cut control circuit

   Current chopping is a kind of mode of current protection, even therefore Angle-domain imaging mode, current chopping circuit conduct Current protection is also what is needed, simultaneously as the essence of current chopping is the big of controlling switch reluctance generator excitation phase current It is small, and the size of phase current will be directly connected to the size of power output.