CN105007007B - A kind of control method of two-phase switched reluctance motor controller - Google Patents

Abstract

The invention discloses a two-phase switched reluctance motor controller and its control method, comprising: a power module, a logic control module, a detection module, a power module and a drive module; The low-voltage direct current required by the module, the detection module and the drive module; the operation state of the logic control module is set to the pre-start state, start state, operation state and overcurrent state respectively; in the case of the operation state, the logic control module different, different control signals are output, and the control signals control the operation of the two-phase switched reluctance motor through the drive module. The invention has beneficial effects: the motor running state control includes zero-speed running state, low-speed running state, and high-speed running state. Different speed calculation methods are adopted in different states, and the different control methods make the motor running output stable and reliable.

Description

A control method for a two-phase switched reluctance motor controller

technical field

The invention relates to the technical field of controllers, in particular to a two-phase switched reluctance motor controller and a control method thereof.

Background technique

Motors for electric angle grinders require high speed, high power, and small size, and series motors are usually used. There are windings on the rotor of the series motor, which adopts a carbon brush structure, which is easy to wear and tear, and the carbon brush must be replaced frequently, which brings inconvenience to use. The structure of the switched reluctance motor is simple and strong. There are only silicon steel sheets on the rotor without windings and permanent magnets. It has high reliability and high efficiency in a wide range of speed and power. The switched reluctance motor is a mechatronics system, and a dedicated controller must be designed, which increases the cost to a certain extent, but the series motor needs to replace the carbon brush frequently. In the long run, the switched reluctance motor system has a certain cost advantage .

The existing switched reluctance motor controller uses an isolated transformer-type isolated power supply to supply power to the control circuit, and the drive of each upper-side power switch tube is powered by its own independent power supply. When the motor is running at low speed, the traditional current chopping method is used. Control requires an accurate current detection circuit with isolation. The isolated power supply takes up a large volume and high cost. The cost of the detection chip required by the current detection circuit is relatively high. The cost of the controller limits the application of switched reluctance motors to a certain extent.

Contents of the invention

The purpose of the present invention is to solve the above problems, and propose a two-phase switched reluctance motor controller and its control method, to realize the long-term safe, reliable and stable operation of the two-phase switched reluctance motor, and to replace the original electric angle grinder The machine uses series excitation motor, which reduces the production cost.

In order to achieve the above object, the present invention adopts the following technical solutions:

A two-phase switched reluctance motor controller, including: a power module, a logic control module, a detection module, a power module and a drive module;

The power module is connected to the power module, and the logic control module is connected to the detection module and the drive module respectively;

The power module converts the high-voltage direct current generated by the power module into the low-voltage direct current required by the logic control module, the detection module and the drive module;

The operating state of the logic control module is respectively set to a pre-start state, a start state, an operating state and an overcurrent state; in the operating state, the logic control module outputs different control signals according to the input signal of the detection module, and the control The signal passes through the drive module to control the switching tube and then drives the operation of the two-phase switched reluctance motor.

The power module includes: a rectifier circuit, a capacitor charging current limiting circuit, a filter circuit and an asymmetrical half-bridge power conversion circuit connected in sequence to realize the function of converting AC to DC and supplying power to the motor and other modules;

The rectifier circuit is a full-bridge rectifier circuit, the capacitor charging current-limiting circuit is two current-limiting resistors connected in series, the filter circuit is a filter capacitor, and the asymmetrical half-bridge power conversion circuit includes:

The diode is connected in series with the controllable switch tube to form a series branch one, and the resistors are connected in series with the controllable switch tube and the diode to form a series branch two, the series branch one and the series branch two are connected in parallel to form a parallel branch, and the two parallel connections The branches are connected in parallel.

The logic control module includes a control chip and peripheral minimum circuits to realize the functions of detection signal input processing and control signal output so as to control the normal operation of the motor. The control chip needs to have the following input and output pins: 1 overcurrent input interrupt pin, 2 position signal interrupt input pins, 1 relay control pin, 2 high and low level output pins, and 2 PWM output pins A total of 9-pin chips, that is, the system can use 8-bit single-chip microcomputer to realize the function of controlling the two-phase switched reluctance motor.

The detection module includes: a current detection circuit and a rotor position detection circuit, which detect the functions of the motor winding current and the rotor position;

The current detection circuit includes: a comparator, a diode D1, a diode D2, a capacitor C1 and a resistor R5;

After the two-phase current of the motor is sampled, the comparator is compared with the upper limit of the current, and the output value of the comparator is combined into a signal output after passing through the diode D1 and the diode D2 respectively; one end of the capacitor C1 is connected to the output end of the diode D1, and the other is One end is grounded; one end of the resistor R5 is connected to the output end of the diode D2, and the other end is grounded.

The rotor position detection circuit includes: a first output clamp circuit, a second output clamp circuit, a first Hall element and a second Hall element;

The control signals output by the logic control module are respectively grounded after passing through the first output clamping circuit and the second output clamping circuit;

One end of the resistor R48 is connected to the second output clamping circuit, and the other end is connected to the second Hall element;

One end of the resistor R49 is connected to the first output clamping circuit, and the other end is connected to the first Hall element;

After the resistor R44 and the resistor R45 are connected in series, one end is connected between the resistor R48 and the second Hall element, and the other end is connected between the resistor R49 and the first Hall element.

The drive module includes: the PWM and SD control signals output by the logic control module are respectively connected to the drive chip through the output and output clamping circuits, and the drive chip drives the controllable switch tube according to the received control signal.

The output clamping circuit includes two diodes connected in series in the same direction.

The power used by the power module, the logic control module, the detection module and the drive module is supplied by a DC chopper power chip without electrical isolation.

A control method for a two-phase switched reluctance motor controller, comprising:

Set the running state of the motor logic control module to the pre-start state, start state, running state and overcurrent state; in the running state, the logic control module sets the motor running state at zero speed according to the different motor speeds state, low-speed state and high-speed running state; different controls for different speeds, including:

In the zero-speed state, the relative position of the stator and rotor of the motor is reflected by the Hall state to determine the energization of a certain phase of the motor. The energization time is fixed, so that the motor can be started with as much torque as possible. When the motor starts, it enters low-speed operation. state.

In the low-speed state, the input bus voltage is known. After the motor speed is detected, the maximum operating current (given when the motor is designed) and the speed are known. Through the characteristics of the motor, the maximum current and speed of the motor can be determined. Voltage value, the duty cycle is the ratio of the maximum voltage value to the bus voltage value at this speed and is not greater than 1, so that the duty cycle can be determined, so that the motor can ensure the maximum output torque of the motor under the condition of no overcurrent. , the turn-on and turn-off angles are determined by the changes of the Hall signal.

In the high-speed state, the normal operating speed of the motor is given, and the operating speed is compared with the motor speed detected by the Hall element to adjust the speed to form an outer loop control of the motor speed;

Determine the motor current at the current speed and the current duty cycle, and perform current inner loop control, that is, first judge whether the current current value reaches the maximum current of the current speed, if it exceeds the maximum current of the current speed, reduce the duty cycle, if not The maximum current of the current speed increases the duty cycle, the increase or decrease of the duty cycle is regulated by the current regulator (PI regulator), and the maximum output of the duty cycle is limited to 1, and the minimum output is 0. At this time, the duty cycle of the motor is determined. The on-off angle is adjusted by the speed. When entering high speed, the on-off angle is advanced when the speed is lower. The on-angle advances by 45 degrees in electrical angle, and the off-angle advances by 90 degrees in electrical angle. , realized by controlling the timer of the chip;

The pre-start state, start state, running state and overcurrent state of the motor logic control module are as follows:

The logic control module is connected to the power frequency power supply. After the filter circuit voltage reaches the working voltage of the switching power supply chip, the switching power supply outputs the working voltage of the control chip of the logic control module, and the control chip enters the power-on reset state. After reset, the control chip enters the pre-start state ;

The control chip controls the pull-in of the relay, and enters the starting state after the pre-starting state;

In the starting state, when the motor speed is not zero, the starting state ends and enters the running state;

In the two-phase current of the motor, as long as one phase overcurrent occurs, it will output an overcurrent signal to the control chip, and the control chip will enter the overcurrent state. In the overcurrent state, the control chip will turn off all the switches, and the PWM duty cycle limit value Set to zero, at this time the motor has no power input, the current of each phase will gradually decrease, keep this state for 2S, and the system will re-enter the pre-start state after 2S.

The beneficial effects of the present invention are:

(1) Two-phase switched reluctance motor is used instead of series motor of angle grinder, which is maintenance-free and low cost;

(2) The two-phase structure is adopted, which reduces the number of power switch tubes of the controller and reduces the cost;

(3) The power supply of the controller is realized by DC chopping, without an isolation transformer, small in size, simple in structure and low in cost.

(4) The controller current is sampled in two phases, and a current overcurrent interrupt input signal is synthesized to reduce controller resources and ensure system safety and reliability;

(5) The system state control is adopted to make the system safe and stable; the motor speed is controlled in stages, and different speeds are controlled differently to realize the safe and reliable operation of the motor;

(6) The maximum value of the PWM duty cycle is determined by the motor characteristics and the motor speed, so as to ensure the maximum output torque of the motor and meet the requirements of no current flow, so that the motor can run reliably and reduce external detection devices.

(7) In order to reduce the cost, the controller adopts the method of converting part of the hardware circuit into software, which improves the product competitiveness.

Description of drawings

Fig. 1 is a kind of two-phase switched reluctance motor controller power main circuit of the present invention and relay control circuit structure schematic diagram;

Fig. 2 is a schematic diagram of the structural principle of a two-phase switched reluctance motor controller power tube drive circuit of the present invention;

Fig. 3 is a kind of two-phase switched reluctance motor controller control of the present invention and the schematic structural diagram of the power supply principle of detection circuit;

4 is a schematic structural diagram of a Hall detection circuit used for rotor position detection by a two-phase switched reluctance motor controller of the present invention;

Fig. 5 is a schematic structural diagram of the current detection principle of a two-phase switched reluctance motor controller of the present invention;

Fig. 6 is a control structure block diagram of a two-phase switched reluctance motor control method of the present invention;

Fig. 7 is a structural schematic diagram of a two-phase switched reluctance motor with stator and rotor teeth of 8/4 structure according to the present invention;

Fig. 8 is a schematic diagram of Hall signals of a two-phase switched reluctance motor controller of the present invention;

9 is a schematic diagram of motor state transition conditions of a two-phase switched reluctance motor control method of the present invention;

Fig. 10 is a schematic diagram of a control method of a two-phase switched reluctance motor of the present invention when the motor is in a zero-speed state;

Fig. 11 is a schematic diagram of a control method of a two-phase switched reluctance motor of the present invention in a low-speed state;

Fig. 12 is a schematic diagram of the motor control mode in a high-speed state of a two-phase switched reluctance motor control method of the present invention;

detailed description:

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

A two-phase switched reluctance motor controller, comprising: a power module, a logic control module, a detection module, a power module and a drive module; the power module is connected to the power module, and the logic control module is connected to the detection module and the drive module respectively; the power module Convert the high-voltage direct current generated by the power module into the low-voltage direct current required by the logic control module, detection module and drive module;

The power module realizes the energy supply of the motor, and the power module converts the high-voltage direct current generated by the power module into the low-voltage direct current required by the logic control module, the detection module and the drive module; the detection module transmits the motor rotor position and the motor current detection value to the logic control module, the logic control module outputs signals to the drive module, and the drive module drives the power switch tube of the power module according to the logic control signal to drive the motor to run.

The main circuit structure of the power module of the two-phase switched reluctance motor controller is simple, and the power frequency AC input is rectified and filtered to generate a bus DC voltage for use by the motor and the controller.

The main circuit of the controller power module and the control circuit of the relay (JLK1) shown in Figure 1, when the alternating current is supplied, the capacitor (C7) is charged through the resistor after rectification, and the capacitor voltage rises gradually. When the bus voltage reaches the working voltage of the switching power supply chip, The control chip starts working.

The power module includes: sequentially connected rectifier circuit, capacitor charging current limiting circuit, filter circuit and asymmetrical half-bridge power conversion circuit to realize the function of converting AC to DC and supplying power to the motor and other modules;

The rectifier circuit is a full-bridge rectifier circuit, the capacitor charging current-limiting circuit is two current-limiting resistors connected in series, the filter circuit is a filter capacitor, and the asymmetrical half-bridge power conversion circuit includes: a freewheeling diode connected in series with a controllable switch tube to form a series branch First, the sampling resistor is sequentially connected in series with the controllable switch tube and the freewheeling diode to form the second series branch, the first series branch and the second series branch are connected in parallel to form a parallel branch, and the two parallel branches are connected in parallel.

As shown in Figure 1, PV1 and PV2 are input interfaces of power frequency power supply, Q1, Q2, Q3, and Q4 are controllable switch tubes, Q1 and Q2 are two-phase upper bridge switch tubes of two-phase motors, and Q3 and Q4 are two-phase motor switch tubes. Two-phase lower bridge switching tubes, Q1, Q3 control one phase winding of the motor, Q2, Q4 control the other phase winding of the motor, when one phase is turned on, the current flows from the power supply through the upper bridge switching tube, the motor winding, and the lower bridge switching tube. to the power supply, thereby forming a loop. R6 and R7 are sampling resistors, which respectively take the current of the two-phase windings of the motor. D2-1, D3-1, D6-1, and D7-1 are respectively the freewheeling diodes of the motor winding.

Figure 2 shows the drive circuit of the power controllable switch tube of the two-phase switched reluctance motor controller. The control signals PWM and SD output from the control chip act on the controllable switch tube through the drive chip. In order to prevent the on-off of the switching tube from interfering with the control chip, D8 and D11 diodes are used to clamp the control signal output to ensure that the output signal is within the working voltage range of the control chip. In the figure, U5 is the driver chip, and the driver chip outputs the driving voltage according to the control signal, which are respectively the driving end of the upper bridge and the driving end of the lower bridge. The upper bridge drive end and the lower bridge drive end respectively control the upper bridge switch tube and the lower bridge switch tube of a phase winding, and the current of each phase of the motor can be controlled through the switch tube.

Figure 3 shows the power supply of the two-phase switched reluctance motor controller system. The power supply adopts the bus voltage, which is stepped down to the required voltage through the DC switch chip to form a chopper circuit, and is non-electrically isolated from the main circuit of the controller power module. The method simplifies the structure of the controller driving power supply. The switching power supply chip in the figure uses LNK306.

Figure 4 and Figure 5 show the controller detection circuit. Figure 4 is the motor rotor detection circuit. The rotor detection circuit uses two Hall elements to detect the rotor rotation direction while detecting the rotor position. Figure 5 shows the current protection circuit for each phase of the motor. The current detected by each phase of the motor is compared with the current upper limit value. As long as one phase is over-current, it will output an over-current signal to the control chip. The two-phase current detection signals do not interfere with each other. The two-phase overcurrent signals are combined into one signal output through diodes D1, D2, C1, and R5. A two-phase switched reluctance motor controller has a simple hardware structure, and a detection module and a power supply module are greatly simplified. The cost of hardware is effectively reduced.

Figure 6 is a flow chart of the two-phase switched reluctance motor control method. After the controller is connected to the industrial frequency power supply, the filter capacitor voltage reaches the working voltage of the switching power supply chip, the switching power supply outputs the working voltage of the controller chip, and the controller enters the Power-on reset state. After reset, the control chip enters the pre-start state. After waiting for 0.1s in the pre-start state, the control chip controls the relay to pull in. After the pre-start state ends, it enters the start state. In the start state, it mainly solves the problem of starting the motor. First The running state of the motor is defined as the zero-speed state. According to the speed detection, when the speed is not zero, the start-up state ends and enters the running state. In the running state, different control methods are implemented according to the motor speed and output requirements.

Figure 7 and Figure 8 show the structure of a two-phase switched reluctance motor with 8/4 stator and rotor teeth and its Hall detection signal. The motor operation structure diagram, the alternate rings represent the magnetic rings fixed on the motor rotor, and respectively represent the different polarities of the magnetic poles on the outer edge of the rings.

When the motor is running, the magnetic ring runs with the rotor, and the Hall element on the stator induces the magnetic ring to output high and low levels, reflecting the position of the rotor. The difference between the positions of the two Halls is 22.5±K*45 degrees mechanical angle (K is an integer). The Hall signal period is a mechanical angle of 90 degrees. The two Hall signals form a square wave signal with a phase difference of 90 degrees, forming 4 states. The motor rotation direction shown in the figure is clockwise, and different state sequences are formed according to the motor speed direction, and corresponding operations are performed according to the state.

The Hall positioning method is: energize the A-phase winding of the two-phase switched reluctance motor, the rotor is fixed due to the magnetic pull, the Hall element is fixed on the stator, and the magnetic ring on the rotor is rotated along the normal running direction of the rotor. At this time, the rotor remains still due to the magnetic pull, so that the signal of the Hall element 1 just changes from a low level to a high level, which is the fixed position of the magnetic ring, and this position is also the commutation point of the motor at low speed.

At zero speed, directly read the Hall state to determine the conduction of A and B phases. At low speed, enter the Hall interrupt and read the Hall state in the Hall interrupt program to determine the conduction of A and B phases. On and off, at zero speed and low speed, Hall element 1 energizes phase A at low level, and energizes phase B at high level.

At high speed, the A and B turn-on and turn-off angles are calculated through the speed and Hall signals. The turn-on angle of each phase is advanced by 11.25 degrees mechanical angle (45 degrees electrical angle), and the conduction is 33.75 degrees mechanical angle; the specific implementation is as follows, When the Hall state changes to 3: the logic control chip measures the conduction time of phase A through the known speed. When the Hall state changes to 2: the logic control chip ensures that phase B has been turned off and phase A has been turned on through the program, and at the same time counts the off time of phase A. When the Hall state becomes 0, the logic control chip counts the B-phase conduction angle time through the known speed. When the Hall state becomes 1: the logic control chip ensures that phase A has been turned off and phase B has been turned on through the program, and at the same time time the off time of phase B.

Among them, when the Hall state is 0, it means that Hall element 1 and Hall element 2 are both in the low level state; when the Hall state is 1, it means that Hall element 1 is in the high level state, and Hall element 2 is in the low level state. level state; when the Hall state is 2, it means that Hall element 1 is in a low level state, and that Hall element 2 is in a high level state; when the Hall state is 3, it means that Hall element 1 and Hall element 2 are both in a high state.

Figure 9 is a schematic diagram of the speed state transition of the two-phase switched reluctance motor control method, where the transition speed point r is determined by the characteristics of the motor and the control needs, and can be changed in the program. The figure shows the speed conversion structure point of a two-phase switched reluctance motor with 8/4 structure of stator and rotor teeth. The transition speed points from zero speed to low speed and from low speed to high speed are 139rpm and 3750rpm respectively. The transition speed points from low speed to zero speed and from high speed to low speed are 125rpm and 1500rpm respectively.

Figure 10 shows the schematic diagram of the motor control process at zero speed. At zero speed, the different phases of the motor are determined to be energized according to the read Hall state. , enter the low-speed running state.

Figure 11 shows the schematic diagram of the motor control process at low speed. At low speed, the output torque of the motor is guaranteed to reach the maximum value. The input bus voltage is known. After the motor speed is detected, the maximum operating current of the motor is known (the Output) and speed, through the motor characteristics, the maximum voltage value of the motor at the maximum current and speed can be determined, and the duty cycle is the ratio of the maximum voltage value to the bus voltage value at this speed and is not greater than 1, so that the duty cycle can be determined Ratio, so that the motor can ensure the maximum output torque of the motor under the condition of no current flow. In the low speed state, the on-off angle is determined by the change of the Hall signal.

Figure 12 is a schematic diagram of the motor control flow in the high-speed state. In the high-speed state, the normal operating speed of the motor is given, and the operating speed is compared with the motor speed detected by the Hall element. ring control;

Determine the motor current at the current speed and the current duty cycle, and perform current inner loop control, that is, first judge whether the current current value reaches the maximum current at the current speed, and if it exceeds the maximum current at the current speed, reduce the duty cycle. If the maximum current of the current speed is not reached, the duty cycle is increased. The increase or decrease of the duty cycle is regulated by the current regulator (PI regulator), and the maximum output of the duty cycle is limited to 1, and the minimum output is 0. In order to determine the duty cycle of the motor, the turn-on and turn-off angles are adjusted by the speed. When entering high speed, the turn-on and turn-off angles are advanced at lower speeds, wherein the turn-on angle is advanced by 45 degrees in electrical angle, and the turn-off angle is advanced by 90 degrees in electrical angle. The timer of the control chip is realized; the motor runs stably. This method reduces the current sampling module of the motor, simplifies the hardware circuit, and makes part of the hardware circuit software-based.

Although the specific implementation of the present invention has been described above in conjunction with the accompanying drawings, it does not limit the protection scope of the present invention. Those skilled in the art should understand that on the basis of the technical solution of the present invention, those skilled in the art do not need to pay creative work Various modifications or variations that can be made are still within the protection scope of the present invention.

Claims (3)

1. A control method for a two-phase switched reluctance motor controller, characterized in that, The two-phase switched reluctance motor controller includes: a power module, a logic control module, a detection module, a power supply module and a drive module; the power module is connected to the power supply module, and the logic control module is connected to the detection module and the drive module respectively; the power supply The module converts the high-voltage direct current generated by the power module into the low-voltage direct current required by the logic control module, detection module and drive module; sets the operating state of the logic control module to pre-start state, start state, running state and over-current state; In the running state, the logic control module outputs different control signals according to the input signal of the detection module, and the control signal controls the switching tube through the driving module to drive the operation of the two-phase switched reluctance motor; The control method includes: setting the running state of the motor logic control module as pre-start state, start state, running state and overcurrent state respectively; in the running state, the logic control module sets the motor running state to Set at zero speed state, low speed state and high speed running state; carry out different controls on different speeds, including: In the zero speed state, according to the relative position of the stator and rotor of the motor, a certain phase of the motor is energized, and the energization time is fixed. Make the motor start with as much torque as possible. When the motor starts, it enters the low-speed running state; in the low-speed state, after detecting the motor speed, determine the maximum voltage value of the motor at the maximum current and speed, according to the maximum voltage value Determine the duty cycle with the input bus voltage value, so that the motor can ensure the maximum output torque of the motor under the condition of no current flow; in the high-speed state, the normal operating speed of the motor is given, and the operating speed is the same as the motor detected by the Hall element. After the speed is compared, the speed is adjusted to form the outer loop control of the motor speed; the motor current at the speed and the current duty ratio are respectively determined, and the current inner loop control is performed to determine the motor duty ratio and the on-off angle. 2. The control method of a two-phase switched reluctance motor controller as claimed in claim 1, wherein, when performing current inner loop control, it is first judged whether the current current value reaches the maximum current of the current rotating speed, if it exceeds the current The maximum current of the speed reduces the duty cycle. If the maximum current of the current speed is not reached, the duty cycle is increased. The increase or decrease of the duty cycle is regulated by the PI regulator, and the maximum output of the duty cycle is limited to 1. The minimum output is 0; the turn-on and turn-off angles are adjusted by the speed, and the turn-on and turn-off angles are advanced when entering a high-speed state and at lower speeds. 3. the control method of a kind of two-phase switched reluctance motor controller as claimed in claim 1, it is characterized in that, the pre-start state, starting state, running state and overcurrent state of motor logic control module are specifically: logic control After the module is connected to the power frequency power supply, the filter circuit voltage reaches the working voltage of the switching power supply chip, the switching power supply outputs the working voltage of the control chip of the logic control module, the control chip enters the power-on reset state, and the control chip enters the pre-start state after reset; control The chip controls the relay to pick up, and the pre-start state ends and enters the start state; in the start state, when the motor speed is not zero, the start state ends and enters the running state; among the two-phase currents of the motor, as long as one phase overcurrent occurs, it will be activated. The logic control module outputs an over-current signal, and the logic control module enters the over-current state; in the over-current state, all switches are turned off, and the PWM duty cycle limit value is set to zero. At this time, the motor has no power input, and the current of each phase will be Decrease gradually, keep this state for a set time, and the system will re-enter the pre-start state.