CN111245300A - Motor starting control circuit and method and electrical equipment - Google Patents

Abstract

The invention discloses a motor start control circuit, a motor start control method and electrical equipment. Wherein, this circuit is including the power, rectifier, first bus capacitance and the inverter that set gradually, the rectifier with connect through direct current bus's first line and second line between the inverter, first bus capacitance's first end and second end are connected respectively first line and second line, its characterized in that, the circuit still includes: and the first end of the booster circuit is connected with the rectifier through the first line, the second end of the booster circuit is connected with the first end of the first bus capacitor, and the third end of the booster circuit is connected with the second line and is used for controlling the voltage of the two ends of the first bus capacitor to be increased after the motor is started. The invention can effectively avoid the condition that the motor enters a weak magnetic control state when running at high frequency, and reduce reactive power output.

Description

A motor starting control circuit, method and electrical equipment

technical field

The present invention relates to the technical field of electronic circuits, and in particular, to a motor starting control circuit, method and electrical equipment.

Background technique

The traditional variable frequency motor start-up control will be affected by the input voltage. If the input voltage is high, the bus voltage is also high. If the input voltage is low, the bus voltage is also low. In the existing control circuit, the rectified bus voltage is usually used to start the compression. However, in the process of high-frequency operation, the magnetic flux Φ of the motor iron core begins to weaken, and the motor speed is higher than the rated speed. At this time, the motor enters the field weakening speed regulation; when the inverter regulates the speed of the asynchronous motor, once it enters the field weakening speed regulation , the output voltage of the inverter will not change, generally the rated voltage of the motor. When the motor current increases and exceeds the rated current, the electromagnetic torque decreases when the speed increases, and the motor power is constant power, so some people call the weak field speed regulation also called constant power speed regulation.

After entering the field weakening control, the reactive output is increased, and the input current of the power supply and the input current of the motor are increased as a whole, which will lead to an increase in the wiring diameter of the equipment and increase the overall cost.

Aiming at the problem that the high-frequency starter motor easily enters the field weakening control in the prior art, no effective solution has been proposed yet.

SUMMARY OF THE INVENTION

The embodiments of the present invention provide a motor starting control circuit, method, and electrical equipment, so as to solve the problem that the high-frequency starting motor is easy to enter the field weakening control in the prior art.

In order to solve the above technical problems, the present invention provides a motor starting control circuit, wherein the circuit includes: a power supply, a rectifier, a first bus capacitor and an inverter arranged in sequence, and the rectifier and the inverter are connected between The first line and the second line of the DC bus are connected, and the first end and the second end of the first bus capacitor are respectively connected to the first line and the second line, and the circuit further includes:

A booster circuit, the first end of which is connected to the rectifier through the first line, the second end of which is connected to the first end of the first bus capacitor, and the third end of which is connected to the second line, and is used in the motor After the startup is completed, the voltage across the first bus capacitor is controlled to increase.

Further, the boost circuit is used to control the voltage across the first bus capacitor to increase, so as to make the difference between the value of the voltage across the first bus capacitor after the boost and the value of the back electromotive force of the motor The value is greater than the preset value.

Further, the boost circuit includes:

an inductor, the first end of which is connected to the rectifier through the first line, and the second end of which is connected to the first end of the unidirectional conduction element;

the unidirectional conduction element, the second end of which is connected to the first end of the first bus capacitor;

a first switch, the first end of which is connected between the inductor and the one-way conducting element, the second end of which is connected to the second line, and the third end of which is connected to the first control signal source, wherein the first switch The control signal source is used to control the turn-on or turn-off of the first switch.

Further, the first switch is configured to be turned on before the motor is started, and turned off after the motor is started.

Further, the motor starting control circuit further includes: a second switch, the first end of which is connected to the rectifier through the first line, the second end of which is connected to the inductor, and the third end of which is connected to a second control signal source .

Further, the second switch is used to change the duty cycle under the control of the second control signal source.

Further, the duty cycle of the second switch is determined according to the ratio between the target value of the voltage across the first bus capacitor and the output voltage of the rectifier, wherein the target value of the voltage across the first bus capacitor is determined according to the motor. voltage requirements are determined.

Further, the second control signal source is a DSP controller.

Further, the motor starting control circuit further includes: a second bus capacitor, the second bus capacitor is arranged in parallel with the first bus capacitor.

The present invention also provides an electrical device, which includes a motor, and also includes the above-mentioned motor start-up control circuit.

The present invention also provides a motor startup control method, which is applied to the above-mentioned motor startup control circuit, and the method includes:

Determine whether the motor is in a high frequency operation state;

When the motor is in a high-frequency operation state, the booster circuit is controlled to start up to boost the voltage across the first bus capacitor.

Further, controlling the boost circuit to start up to boost the voltage across the first bus capacitor includes:

The voltage across the first bus capacitor is controlled to increase, so that the difference between the increased voltage across the first bus capacitor and the value of the back electromotive force of the motor is greater than a preset value.

Further, before controlling the boost circuit to start, it includes:

Control the first switch to be turned off.

Further, after controlling the first switch to be turned off, the method further includes:

Get the voltage requirements of the motor;

The duty cycle of the second switch is adjusted according to the voltage demand of the motor to control the voltage across the first bus capacitor.

Further, adjusting the duty cycle of the second switch according to the voltage demand of the motor, including:

Determine the target value of the voltage across the first bus capacitor according to the voltage demand of the motor;

The duty cycle of the second switch is adjusted according to the ratio of the target value of the voltage across the first bus capacitor and the output voltage of the rectifier.

The present invention also provides a computer-readable storage medium on which a computer program is stored, and when the program is executed by a processor, the above-mentioned motor startup control method is implemented.

By applying the technical solution of the present invention, by setting a booster circuit, after the motor starts, the voltage value across the bus capacitor is increased, so the motor will not easily enter the field weakening control state even if it is running in a high frequency state, which can effectively avoid the motor When running at high frequency, it will reduce the reactive power output when it enters the field weakening control state.

Description of drawings

Fig. 1 is the structure diagram of the existing motor starting control circuit;

FIG. 2 is a structural diagram of a motor starting control circuit according to an embodiment of the present invention;

3 is a structural diagram of a motor starting control circuit according to another embodiment of the present invention;

4 is a structural diagram of a motor starting control circuit according to another embodiment of the present invention;

FIG. 5 is a flowchart of a motor startup control method according to an embodiment of the present invention.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms "a," "the," and "the" as used in the embodiments of the present invention and the appended claims are intended to include the plural forms as well, unless the context clearly dictates otherwise, "a plurality" Generally at least two are included.

It should be understood that the term "and/or" used in this document is only an association relationship to describe the associated objects, indicating that there may be three kinds of relationships, for example, A and/or B, which may indicate that A exists alone, and A and B exist at the same time. B, there are three cases of B alone. In addition, the character "/" in this document generally indicates that the related objects are an "or" relationship.

It should be understood that although the terms first and second may be used to describe switches in the embodiments of the present invention, these switches should not be limited by these terms. These terms are only used to distinguish switches that are located in different positions and have different functions. For example, the first switch may also be referred to as the second switch, and similarly, the second switch may also be referred to as the first switch without departing from the scope of the embodiments of the present invention.

Depending on the context, the words "if", "if" as used herein may be interpreted as "at" or "when" or "in response to determining" or "in response to detecting". Similarly, the phrases "if determined" or "if detected (the stated condition or event)" can be interpreted as "when determined" or "in response to determining" or "when detected (the stated condition or event)," depending on the context )" or "in response to detection (a stated condition or event)".

It should also be noted that the terms "comprising", "comprising" or any other variation thereof are intended to encompass a non-exclusive inclusion, such that a commodity or device comprising a list of elements includes not only those elements, but also those not explicitly listed other elements, or other elements inherent to such goods or devices. Without further limitation, an element qualified by the phrase "comprising a..." does not preclude the presence of additional identical elements in the article or device that includes the element.

The optional embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

Example 1

This embodiment provides a motor starting control circuit. Before introducing the motor starting control circuit of the present invention, an existing motor starting control circuit is first introduced. FIG. 1 is a structural diagram of the existing motor starting control circuit, as shown in FIG. 1, including: a power supply 11, a rectifier 12, a first bus capacitor C1, and an inverter 13 arranged in sequence, wherein the rectifier 12 includes: a first rectifier bridge B1 and a second rectifier bridge B2 arranged in parallel, wherein the first rectifier bridge B1 and the second rectifier bridge B2 are arranged in parallel. A rectifier bridge B1 includes No. 1 diode D1 and No. 2 diode D2 connected in series in the same direction. The second rectifier bridge B2 includes No. 3 diode D3 and No. 4 diode D4 connected in series in the same direction. The neutral line N of the power supply 11 is connected to the No. 1 diode. Between D1 and the second diode D2, the live wire L of the power supply 11 is connected between the third diode D3 and the fourth diode D4, and between the rectifier 12 and the inverter 13 through the first line 141 and the second line 142 of the DC bus 14 For connection, the first end of the first bus capacitor C1 is connected to the first line 141 , and the second end is connected to the second line 142 .

The inverter 13 includes a first inverter bridge B3, a second inverter bridge B4, and a third inverter bridge B5, which are arranged in parallel. The first inverter bridge B3 includes a first switch transistor Q1 and a second switch transistor Q2 connected in series in sequence. and the first resistor RS1, the second inverter bridge B4 includes a third switch tube Q3, a fourth switch tube Q4 and a second resistor RS2 connected in series, and the third inverter bridge B5 includes a fifth switch tube Q5, Six switch tubes Q6 and second resistor RS3, the first switch tube Q1, the second switch tube Q2, the third switch tube Q3, the fourth switch tube Q4, the fifth switch tube Q5, the sixth switch tube Q6 and the fifth diode respectively D5, No. 6 diode D6, No. 7 diode D7, No. 8 diode D8, No. 9 diode D9, No. 10 diode D10 are in reverse parallel connection, the first phase line U of the motor is connected to the first switch tube Q1 and Between the second switch tubes Q2, the second phase line V is connected between the third switch tube Q3 and the fourth switch tube Q4 through the fifth resistor RS5, and the third phase line W is connected to the fifth switch tube through the sixth resistor RS6 between Q5 and the sixth switch tube Q6.

With the above rectifier, the voltage across the first bus capacitor C1 is in a constant state. If the voltage output by the power supply 11 fluctuates, the voltage across the first bus capacitor C1 also changes. When the motor runs at high frequency, the two terminals of the motor A very high back electromotive force is generated at the terminal, and when it is close to the voltage across the first bus capacitor C1, the motor will enter the field weakening control state, increase the reactive output, and increase the output current of the power supply and the input current of the motor as a whole, which will cause the equipment The diameter of the wiring wire increases, which increases the overall cost, so the above-mentioned motor control circuit needs to be further improved.

FIG. 2 is a structural diagram of a motor starting control circuit according to an embodiment of the present invention. In order to improve the problem that the motor is easy to enter the field weakening control state when the motor is running at a high frequency, as shown in FIG. 2 , on the basis of the existing motor starting control circuit , the circuit further includes: a booster circuit 15, the first end of which is connected to the rectifier 12 through the first line 141, the second end of which is connected to the first end of the first bus capacitor C1, and the third end of which is connected to the second line 142, It is used to control the voltage at both ends of the first bus capacitor C1 to increase after the motor is started. Since the motor runs at high frequency, a high back electromotive force is generated at both ends of the motor terminals. voltage, the motor will enter the field weakening control state. Therefore, when using the above boost circuit 15 to control the voltage across the first bus capacitor, it is necessary to ensure that the voltage across the first bus capacitor is boosted by the boost circuit. The difference from the value of the back electromotive force of the motor is greater than a preset value, wherein the value of the voltage across the first bus capacitor, the value of the back electromotive force of the motor and the above difference are all greater than zero.

In the motor startup control circuit of this embodiment, by setting a boost circuit, after the motor is started, the voltage value across the bus capacitor is increased, so the motor will not easily enter the field weakening control state even if the motor is running in a high frequency state, which can effectively Avoid the situation that the motor enters the field weakening control state when the motor is running at high frequency, and reduce the reactive power output.

Example 2

This embodiment provides another motor startup control circuit. FIG. 3 is a structural diagram of a motor startup control circuit according to another embodiment of the present invention. As shown in FIG. 3 , in order to realize the boost function, the boost circuit includes:

The first end of the inductor L1 is connected to the rectifier 12 through the first line, and the second end of the inductor L1 is connected to the first end of the one-way conducting element D11.

The one-way conduction element D11, the second end of the one-way conduction element D11 is connected to the first end of the first bus capacitor C1 to prevent the bus capacitor from discharging to the ground. In this embodiment, the one-way conduction element D11 can be diode.

It also includes a first switch Q7, the first end of which is connected between the inductor L1 and the one-way conducting element D11, the second end of which is connected to the second line, and the third end of which is connected to the first control signal source 16, wherein the The first control signal source 16 is used to control the turn-on or turn-off of the first switch Q7. Specifically, under the control of the first control signal source 16, the first switch Q7 is turned on before the motor is started and turned off after the motor is started. , wherein the first control signal source 16 is a voltage source whose output signal is variable.

Since the above booster circuit includes the inductor L1 and the one-way conducting element D11 arranged in series on the first line 141 of the DC bus 14, it also includes the common connection point of the inductor L1 and the one-way conducting element D11 and the first line of the DC bus. The first switch Q7 between the lines 141, before the completion of the motor startup, the boost circuit 15 does not work and does not have the function of boosting, that is, the first switch Q7 is turned on, and the voltage output by the rectifier circuit is the inductor L1. Charge, so that the inductor L1 stores a certain amount of electricity. After the motor starts, the control booster circuit 15 starts to work, the inductor L1 discharges the capacitor of the first bus 141, and increases the voltage across the first bus capacitor C1. Before the motor starts, the The first switch Q7 is in an off state. Therefore, before the control booster circuit 15 starts, the first switch Q7 needs to be turned off to discharge the inductor to the first bus capacitor C1 and increase the voltage across the first bus capacitor C1.

Since the change of the voltage across the first bus capacitor C1 will affect the motor control of the latter stage, when the motor is just starting or running at a low frequency, the running current of the motor will be very small due to the low frequency, which will affect the current sampling accuracy. When DSP control is used, the duty cycle is too small, and stable control cannot be achieved, which increases the difficulty of DSP as a whole. The boost circuit in the above embodiment is designed for high-frequency operation. Therefore, low-frequency operation is not considered. When the voltage demand of the motor is small, if the output voltage of the rectifier is boosted according to the high frequency operation, it is obviously not compatible with the voltage demand of the motor. In order to solve this problem, as shown in Figure 3, On the basis of the above embodiment, the motor starting control circuit further includes: a second switch Q8, the first end of the second switch Q8 is connected to the rectifier 12 through the first line 141, the second end is connected to the inductor L1, and the third end is connected to the Two control signal sources 17 .

In order to change the voltage across the first bus capacitor C1 according to the needs of the motor, the specific function of the second switch Q8 is to change the duty cycle under the control of the second control signal source 17, thereby changing the voltage across the first bus capacitor, That is, the voltage of the input motor ensures that the voltage across the first bus capacitor is low voltage during low-frequency operation, thereby ensuring that the motor operates in a more stable state during low-frequency operation.

The duty cycle of the second switch Q8 is determined according to the ratio of the target value of the voltage across the first bus capacitor C1 and the output voltage of the rectifier 12, wherein the target value of the voltage across the first bus capacitor C1 is determined according to the motor Specifically, the voltage requirement can be determined according to the operating frequency of the motor. According to the characteristics of each motor, each operating frequency corresponds to an operating voltage requirement. The lower the operating frequency, the lower the operating voltage requirement. That is to say, when the duty cycle of the second switch Q8 is controlled by the second control signal source 17, the operating voltage requirement can be obtained first according to the relationship that the operating frequency is lower, and then the first bus capacitor C1 can be determined according to the voltage requirement of the motor. The target value of the terminal voltage is determined, and then the duty cycle of the second switch Q8 is determined according to the ratio of the target value of the voltage across the first bus capacitor C1 and the output voltage of the rectifier.

In this embodiment, the second control signal source 17 is a DSP controller capable of outputting a PWM modulation signal with an adjustable pulse width for controlling the duty cycle of the second switch Q8.

In other embodiments of the present invention, the motor starting control circuit may further include: a second bus capacitor C2, the second bus capacitor C2 is arranged in parallel with the first bus capacitor C1.

Example 3

This embodiment provides another motor starting control circuit. FIG. 4 is a structural diagram of a motor starting control circuit according to another embodiment of the present invention. As shown in FIG. 4 , as shown in FIG. 4 , in the existing power supply 41 On the basis of the motor start-up control circuit of the rectifier 42 and the inverter 43, a BOOST booster circuit 45 is added. The BOOST booster circuit includes: an inductance L41 and a unidirectional conducting element arranged in series on the first line 441 of the DC bus. D41, further comprising a first switch Q41 arranged between the common connection point of the inductor L41 and the one-way conducting element D41 and the second line 442 of the DC bus, wherein the first line 441 and the second line 442 of the DC bus are arranged on the rectifier Between 42 and the inverter 43, before the start of the motor is completed, the operating frequency of the motor is low, the boost circuit 45 does not work, and does not have the function of boosting, that is, the first switch Q41 is turned on, and the voltage output by the rectifier 12 Charge the inductor L41 to store a certain amount of electricity. When the motor is started, the BOOST boost circuit 45 is controlled to work, and the inductor L41 discharges the first bus capacitor C41 and the second bus capacitor C42, increasing the first bus capacitor C41 and the second bus capacitor C42. The voltage across the second bus capacitor C42, because the first switch Q41 is in an off state before the start of the motor is completed, therefore, before the control of the boost circuit to start, it is necessary to control the first switch Q41 to be off, so that the inductor L41 can be connected to the first bus The capacitor C41 and the second bus capacitor C42 are discharged, and the above topology structure can effectively control the voltage across the first bus capacitor C41 and the second bus capacitor C42 arranged in parallel, and can realize boost control. In the initial stage of motor startup, the booster circuit 45 does not work, so the voltage across the first bus capacitor C41 and the second busbar capacitor C42 is the voltage rectified by the rectifier 42, and after the motor starts, the booster circuit 45 starts to work , the voltage across the first bus capacitor C41 and the second bus capacitor C42 is increased, so the motor will not easily enter the field weakening state even in the high frequency state of operation.

The above embodiment only solves the problem that the motor is easy to enter the field weakening in the high frequency operation state, and does not solve the problem of easy start failure and difficulty in low frequency control due to the high bus capacitor voltage when the motor is started or in low frequency operation. Not the best implementation. In order to solve the technical problems mentioned above, as shown in FIG. 4 , a second switch Q42 is set before the BOOST booster circuit 45 to work with the BOOST booster circuit 45 . When the operating frequency is low, the first switch Q41 in the booster circuit 45 is turned on, the second switch Q42 is operated, and the duty cycle of the control signal G42 at the control end of the second switch Q42 is calculated according to the voltage demand of the subsequent stage motor. , in order to ensure that the motor current is not too small, and in order to reduce the difficulty of DSP control, the duty cycle should not be too small. According to the motor start-up requirements, the target value of the voltage across the bus capacitor is calculated as V1, and then according to the ratio of the target value V1 of the voltage at both ends of the bus capacitor to the output voltage V of the rectifier, the duty cycle of the control signal G42 is further calculated, so that To realize the start of the motor when the voltage at both ends of the bus capacitor is low, since different motors are selected in different equipment, their starting performance is also different. Therefore, the target value of the voltage at both ends of the bus capacitor should be V1 according to actual needs. Revise.

When the motor is running at a low frequency, in order to avoid the problem of control instability caused by the small running current of the motor, it is also necessary to adjust the duty cycle of the second switch Q42 to ensure that the voltage across the bus capacitor is lower, so as to ensure the motor runs. More stable at low frequencies.

Through the motor starting control circuit of this embodiment, when the motor is running in a high frequency state, due to the high back electromotive force of the motor, the working states of the first switch Q41 and the second switch Q42 are adjusted so that the first switch Q41 is always in the conducting state, and the The second switch Q42 is continuously turned on and off under the control of the DSP, so as to increase the voltage across the bus capacitor. The boosted voltage V across the bus capacitor needs to be determined according to the back electromotive force of the motor. ground, it can be controlled that the difference between the value of the voltage across the first bus capacitor C41 and the second bus capacitor C42 after the increase and the value of the back electromotive force of the motor is greater than the preset value; when the motor is running at a low frequency, adjust The duty cycle of the second switch Q42 ensures that the voltage across the bus capacitor is lower, thereby ensuring that the motor operates more stably at low frequencies.

During the above low-frequency startup, low-frequency operation or high-frequency operation, the voltage across the bus capacitor can be neither too small nor too large, so as to avoid exceeding the hardware tolerance range, resulting in failure to respond, so as to achieve the best output performance of the motor.

Example 4

This embodiment provides an electrical device, including a motor, and the motor startup control circuit in the above embodiment, which is used to avoid the situation that the motor enters a field weakening control state and reduce reactive power output when the motor runs at a high frequency.

Example 5

The present embodiment provides a motor startup control method, which is applied to the motor startup control circuit in the above embodiment. FIG. 5 is a flowchart of the motor startup control method according to an embodiment of the present invention. As shown in FIG. 5 , the motor startup Control methods include:

S101, it is judged whether the motor is in a high frequency running state.

Wherein, when the motor is a compressor, to determine whether the motor is in a high-frequency operation state, a frequency threshold may be preset, and when the frequency of the compressor exceeds the frequency threshold, it is determined that the compressor is in a high-frequency operation state.

S102 , when the motor is in a high-frequency operation state, control the booster circuit to start, so as to increase the voltage across the first bus capacitor.

Specifically, controlling the boost circuit to start to increase the voltage across the first bus capacitor includes: controlling the voltage across the first bus capacitor to increase, so that the value of the increased voltage across the first bus capacitor is equal to the value of the voltage across the first bus capacitor. The difference between the values of the back electromotive force of the motor is greater than the preset value, that is to say, after boosting, the difference between the value of the voltage across the first bus capacitor and the value of the back electromotive force of the motor is greater than the preset value, wherein, The preset value is determined according to an empirical value or an experimental value, and the determination principle is: when the difference between the value of the voltage at both ends of the first bus capacitor and the value of the back EMF of the motor is greater than the preset value, the motor will not enter the field weakening control. state.

According to the above, the booster circuit includes: an inductance and a one-way conduction element arranged in series on the first line of the DC bus, and further comprising a common connection point of the inductance and the one-way conduction element and the first line of the DC bus. For the first switch between the two wires, before the motor is started, the circuit does not work and does not have the function of boosting, that is, the first switch is turned on, and the voltage output by the rectifier circuit charges the inductor, so that the inductor stores a certain amount of electricity , when the motor is started, the control boost circuit starts to work, the inductor discharges the first bus capacitor, and the voltage across the first bus capacitor is increased. Since the first switch is in the off state before the motor starts, the control boost Before the circuit is started, the method includes: controlling the first switch to be turned off, so that the inductor discharges the first bus capacitor and increases the voltage across the first bus capacitor.

After controlling the first switch to be turned off, the method further includes: acquiring the voltage demand of the motor; adjusting the duty cycle of the second switch according to the voltage demand of the motor to control the voltage across the first bus capacitor, specifically, according to the voltage demand of the motor Adjusting the duty cycle of the second switch according to the voltage demand includes: determining the target value of the voltage across the first bus capacitor according to the voltage demand of the motor; according to the target value of the voltage across the first bus capacitor and the rectifier The ratio of the output voltage adjusts the duty cycle of the second switch, wherein the voltage demand of the motor can be determined according to the operating frequency of the motor, and according to the characteristics of each motor itself, each operating frequency corresponds to an operating voltage demand, and the operating frequency The lower it is, the lower the operating voltage requirement is, that is to say, when the duty cycle of the second switch is controlled by the second control signal source, the operating voltage requirement can be obtained first according to the relationship of the lower operating frequency, and then according to the motor voltage It is required to determine the target value of the voltage across the first bus capacitor, and then determine the duty cycle of the second switch according to the ratio between the target value of the voltage across the first bus capacitor and the output voltage of the rectifier.

Example 6

This embodiment provides a computer-readable storage medium on which a computer program is stored, and when the program is executed by a processor, implements the motor startup control method in the foregoing embodiment.

From the description of the above embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus a necessary general hardware platform, and certainly can also be implemented by hardware. Based on this understanding, the above-mentioned technical solutions can be embodied in the form of software products in essence or the parts that make contributions to the prior art, and the computer software products can be stored in computer-readable storage media, such as ROM/RAM, magnetic A disc, an optical disc, etc., includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to perform the methods described in various embodiments or some parts of the embodiments.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that it can still be The technical solutions described in the foregoing embodiments are modified, or some technical features thereof are equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims (16)

1. The utility model provides a motor start control circuit, is including the power, rectifier, first bus capacitance and the inverter that set gradually, the rectifier with first line and the second line connection through direct current bus between the inverter, first end and the second end of first bus capacitance are connected respectively first line and second line, its characterized in that, the circuit still includes:

and the first end of the booster circuit is connected with the rectifier through the first line, the second end of the booster circuit is connected with the first end of the first bus capacitor, and the third end of the booster circuit is connected with the second line and is used for controlling the voltage of the two ends of the first bus capacitor to be increased after the motor is started.

2. The motor start control circuit of claim 1,

the boost circuit is used for controlling the voltage at the two ends of the first bus capacitor to be boosted so that the difference value between the boosted voltage at the two ends of the first bus capacitor and the back electromotive force value of the motor is larger than a preset value.

3. The motor start control circuit of claim 1 wherein the boost circuit comprises:

the first end of the inductor is connected with the rectifier through the first line, and the second end of the inductor is connected with the first end of the unidirectional conducting element;

the second end of the unidirectional conducting element is connected with the first end of the first bus capacitor;

and a first switch, a first end of which is connected between the inductor and the unidirectional conducting element, a second end of which is connected with the second line, and a third end of which is connected with a first control signal source, wherein the first control signal source is used for controlling the conduction or disconnection of the first switch.

4. A motor start control circuit according to claim 3 wherein the first switch is adapted to be turned on before the motor is started and turned off after the motor is started.

5. The motor start control circuit of claim 3 further comprising:

and a first end of the second switch is connected with the rectifier through the first line, a second end of the second switch is connected with the inductor, and a third end of the second switch is connected with a second control signal source.

6. The motor start control circuit of claim 5 wherein the second switch is configured to vary a duty cycle under control of the second control signal source.

7. A motor start control circuit according to claim 6 wherein the duty cycle of the second switch is determined by the ratio of the target value of the voltage across the first bus capacitor to the output voltage of the rectifier, wherein the target value of the voltage across the first bus capacitor is determined by the voltage requirement of the motor.

8. The motor start control circuit of claim 5 wherein the second control signal source is a DSP controller.

9. The motor start control circuit of claim 1 further comprising:

and the second bus capacitor is connected with the first bus capacitor in parallel.

10. An electrical appliance comprising an electrical machine, characterized in that it further comprises a motor start control circuit according to any one of claims 1 to 9.

11. A motor start control method applied to the motor start control circuit according to any one of claims 1 to 9, characterized by comprising:

judging whether the motor is in a high-frequency running state;

and when the motor is in a high-frequency running state, the booster circuit is controlled to be started so as to boost the voltage at two ends of the first bus capacitor.

12. The motor start control method of claim 11, wherein controlling the boost circuit to start up to boost the voltage across the first bus capacitor comprises:

and controlling the voltage at the two ends of the first bus capacitor to rise, so that the difference value between the voltage at the two ends of the first bus capacitor after rising and the counter electromotive force value of the motor is larger than a preset value.

13. The motor start control method according to claim 11, wherein before controlling the booster circuit to start, comprising:

and controlling the first switch to be switched off.

14. The motor start control method according to claim 12, characterized in that after controlling the first switch to be turned off, the method further comprises:

acquiring a voltage requirement of a motor;

and adjusting the duty ratio of the second switch according to the voltage requirement of the motor so as to control the voltage at two ends of the first bus capacitor.

15. The motor start control method of claim 12, wherein adjusting the duty cycle of the second switch based on the voltage requirement of the motor comprises:

determining a target value of voltage at two ends of the first bus capacitor according to the voltage requirement of the motor;

and adjusting the duty ratio of the second switch according to the ratio of the target value of the voltage at the two ends of the first bus capacitor to the output voltage of the rectifier.

16. A computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, carries out the method of any one of claims 11 to 15.

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