A New PWM Control Method for ECM Motor

Abstract

The invention discloses a novel PWM control method for an ECM motor. The ECM motor comprises a motor controller and a motor unit. A motor control circuit board is provided with a microprocessor, an inverter circuit and an interface circuit. A PWM input port is arranged on the motor control circuit board. A PWM control signal of an external device is input to the microprocessor after being processed by the interface circuit via the PWM input port. A plurality of groups of motor application parameters are stored in the motor controller. The microprocessor first detects the frequency of the input PWM signal, selects a group of corresponding motor application parameters according to the frequency of the input PWM signal, detects the duty cycle of the input PWM signal, and calculates the target value required for the motor to run based on the selected group of corresponding motor application parameters and the duty cycle. The method can enable the ECM motor to match many air-conditioning load models, greatly reduce the motor part number, and bring greater convenience to customers.

Description

Technical Field

[0001] The invention relates to a novel PWM control method for an ECM motor. Background Art

[0002] In recent years, with the increasingly fierce competition in the field of electrical appliances, the technical requirements for products have been continuously improved, such as requiring products to be energy-saving and environmentally friendly, with high controllability and intelligence, short development cycle, and low noise. As a core component, the motor has undoubtedly become a key component to solve the above technical problems. The motor in traditional household air conditioners generally adopts single-phase AC motor PSC. Single-phase AC motors have low efficiency, high energy consumption, high noise, and low controllability and intelligence. With the development of motor technology, DC motors have gradually replaced AC motors. DC motors are equipped with motor controllers, which use motor controllers to achieve the purpose of electronic commutation of current. Therefore, some people in the industry also call them ECM motors (electronically commutated motors) or brushless DC motors (BLDC MOTOR). They have the characteristics of energy saving and environmental protection, high reliability and controllability, low noise, and easy to realize intelligence. They can solve the shortcomings of single-phase AC motors. Therefore, the single-phase AC motors in existing air conditioners are gradually replaced by brushless DC motors or ECM motors.

[0003] After years of market application, the ECM motors with constant torque control or constant air volume control developed by mainstream foreign air-conditioning manufacturers have many load models. In order to facilitate the application on different load models, the newly developed replacement ECM motors need to identify the input parameters to match different load application parameters. The process is complicated and leads to the production of a large number of different types of replacement ECM motors, which is not conducive to the management of manufacturers. In addition, each different type of replacement ECM motor requires a development cycle and development cost. In view of this, can we develop a replacement ECM motor that can match many air-conditioning load models?

[0004] It greatly reduces the number of motor parts, bringing greater convenience to customers. Summary of the invention

[0005] The purpose of the present invention is to provide a new PWM control method for an ECM motor, which uses the frequency of an input PWM signal to first select a set of corresponding motor application parameters, then detects the duty cycle of the input PWM signal, and calculates the target value required for the motor to operate based on the selected set of corresponding motor application parameters and the duty cycle; it can match many air-conditioning load models, greatly reduces the motor part number, and brings greater convenience to customers.

[0006] The purpose of the present invention is achieved through the following technical solutions.

[0007] A novel PWM control method for an ECM motor, the ECM motor comprises a motor controller and a motor monomer, the motor monomer comprises a stator assembly, a rotor assembly and a casing assembly, the stator assembly is mounted on the casing assembly, the stator assembly and the rotor assembly are magnetically coupled, the motor controller comprises a motor control circuit board, the motor control circuit board is arranged with a microprocessor, an inverter circuit and an interface circuit, the microprocessor controls the inverter circuit, the inverter circuit controls the current of each phase coil winding of the stator assembly, a PWM input port is arranged on the motor control circuit board, a PWM control signal of an external device is input to the microprocessor after being processed by the interface circuit using the PWM input port, and the control method is characterized in that: the motor controller stores multiple groups of motor application parameters, the microprocessor first detects the frequency of the input PWM signal, selects a group of corresponding motor application parameters according to the frequency of the input PWM signal, and then detects the duty cycle of the input PWM signal, and calculates the required operation target value of the motor based on the selected group of corresponding motor application parameters and the duty cycle; the motor application parameter refers to a torque application parameter or an air volume application parameter, and the operation target value refers to a torque target value or an air volume target value.

[0008] The above-mentioned microprocessor outputs a feedback signal FG through the interface circuit to represent the state of the motor.

[0009] The feedback signal FG is a PWM signal. The feedback signal FG represents different horsepower segments of the motor through PWM signals of different frequency segments.

[0010] The feedback signal FG is a PWM signal that feeds back the rotational speed, and outputs a square wave PWM signal with a duty cycle of 50%. The frequency f of the square wave PWM signal with a duty cycle of 50% has a fixed corresponding relationship with the rotational speed.

[0011] The feedback signal FG is a PWM signal that feeds back the actual current or power of the motor, and outputs a square wave PWM signal with a duty cycle of 50%. The frequency f of the square wave PWM signal with a duty cycle of 50% has a fixed corresponding relationship with the actual current or power of the motor.

[0012] The above-mentioned multiple groups of motor application parameters refer to at least 3 groups, and each group of motor application parameters includes a maximum value and a minimum value of the motor application parameters.

[0013] The above-mentioned selection of a corresponding motor application parameter according to the frequency of the input PWM signal is the air volume application parameter. The air volume application parameter includes the maximum air volume Qmax and the minimum air volume Qmin. The duty cycle of the input PWM signal is Duty. Then any target air volume:

[0014] Qn = Qmin+(95%-Duty)*(Qmax-Qmin) / (95%-5%).

[0015] After obtaining any target air volume Qn, the motor bus power calibration value Power_goal corresponding to any target air volume is calculated as Power_goal = K0 + K1*Qn + K2*N + K3*Qn*N + K4*N*N; wherein K0, K1, K2, K3, K4 are air volume model function calculation coefficients, N represents the speed, each set of air volume application parameters corresponds to a set of air volume model function calculation coefficients, and the air volume model function calculation coefficients are also stored in the motor controller.

[0016] The real-time power of the above motor is Power_actual=Vdc*Idc, where Vdc is the bus voltage and Idc is the bus current. By comparing the motor bus power calibration value Power_goal and the real-time power Power_actual of the motor, the target speed is continuously adjusted to achieve dynamic balance, and the desired target air volume can be output.

[0017] Compared with the prior art, the present invention has the following effects:

[0018] 1) The motor controller stores multiple groups of motor application parameters. The microprocessor first detects the frequency of the input PWM signal, selects a group of corresponding motor application parameters according to the frequency of the input PWM signal, and then detects the duty cycle of the input PWM signal. The motor needs to calculate the target value for operation based on the selected group of corresponding motor application parameters and the duty cycle; the motor application parameters refer to speed application parameters, torque application parameters, or air volume application parameters, and the operation target value refers to speed target value, torque target value, or air volume target value. It enables the ECM motor to match many air-conditioning load models, greatly reduces the motor part number, and brings greater convenience to customers.

[0019] 2) Other advantages of the present invention are described in detail in the embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a three-dimensional diagram of the ECM motor of the present invention;

[0021] Figure 2 is a three-dimensional diagram of a motor controller of an ECM motor of the present invention;

[0022] Figure 3 is a cross-sectional view of the ECM motor of the present invention;

[0023] Figure 4 is a block diagram of an implementation circuit of a motor controller of an ECM motor of the present invention;

[0024] Figure 5 yes Figure 4 The corresponding circuit diagram;

[0025] Figure 6 It is a schematic diagram of the connection between the ECM motor and the air conditioning system control mainboard of the present invention;

[0026] Figure 7 is a circuit diagram of an interface circuit of an ECM motor of the present invention;

[0027] Figure 8 It is a flow chart of the processing of the input PWM signal by the ECM motor of the present invention. DETAILED DESCRIPTION

[0028] The present invention is further described in detail below through specific embodiments in conjunction with the accompanying drawings.

[0029] Embodiment 1: Figures 1 to 7 As shown, this embodiment relates to an ECM motor 6, which includes a motor controller 62 and a motor unit 61. The motor monomer 61 includes a stator assembly 612, a rotor assembly 613 and a housing assembly 611. The stator assembly 612 is mounted on the housing assembly 611. The stator assembly 612 and the rotor assembly 613 are magnetically coupled. The motor controller 62 includes a motor control circuit board 621. The motor control circuit board 621 is arranged with a microprocessor, an inverter circuit and an interface circuit. The microprocessor controls the inverter circuit, and the inverter circuit controls the current of each phase coil winding of the stator assembly 612. The motor control circuit board 621 is provided with 5 connection ports for connecting with the air conditioning system control mainboard 100. The 5 connection ports are: a ground terminal GND connected to the ground, a PWM input port, a DC bus voltage input port VDC, a low-voltage DC power supply input port VCC and a motor feedback port. The motor feedback port outputs a feedback signal FG to represent the state of the motor. The air conditioning system control mainboard 100 inputs a PWM signal to the ECM motor 6 through the PWM input port. The microprocessor calculates the set target air volume or target speed or target torque according to the input PWM signal. Figure 4 As shown, the rotor position detection circuit detects the rotor position signal and inputs it to the microprocessor. The microprocessor controls the inverter circuit to work, and the inverter circuit controls the on and off of each phase coil winding of the stator assembly 612. The interface circuit has two optocoupler isolation circuits. The PWM input port and the motor feedback port are connected to the microprocessor through the two optocoupler isolation circuits. Figure 7 The chips U601 and U602 are optocoupler chips. Two software program modules are set in the microprocessor, namely the PWM frequency recognition module and the PWM duty cycle recognition module, which are used to recognize the frequency and duty cycle of the input PWM signal respectively.

[0030] like Figure 4 , Figure 5As shown, assuming that the ECM motor is a 3-phase brushless DC permanent magnet synchronous motor, the rotor position detection circuit generally uses 3 Hall sensors HALL, which respectively detect the rotor position of a 360-degree electrical angle cycle, and change the power supply of each phase coil winding of the stator component 12 once every 120 degrees of electrical angle, forming a 3-phase 6-step control mode. After the AC input (AC INPUT) passes through the full-wave rectifier circuit composed of diodes D7, D8, D9, and D10, the inverter circuit is composed of electronic switch tubes Q1, Q2, Q3, Q4, Q5, and Q6. The control ends of the electronic switch tubes Q1, Q2, Q3, Q4, Q5, and Q6 are respectively controlled by 6 PWM signals (P1, P2, P3, P4, P5, and P6) output by the microprocessor. The motor control circuit board 621 has five connection ports: a ground terminal GND connected to the ground, a PWM input port, a DC bus voltage input port VDC, a low voltage DC power input port VCC and a motor feedback port.

[0031] like Figures 1 to 8 As shown, a novel PWM control method for an ECM motor is shown, wherein the ECM motor 6 comprises a motor controller 62 and a motor unit 61, wherein the motor unit 61 comprises a stator assembly 612, a rotor assembly 613 and a housing assembly 611, wherein the stator assembly 612 is mounted on the housing assembly 611, wherein the stator assembly 612 and the rotor assembly 613 are magnetically coupled, wherein the motor controller 62 comprises a motor control circuit board 621, wherein the motor control circuit board 621 is provided with a microprocessor, an inverter circuit and an interface circuit, wherein the microprocessor controls the inverter circuit, and the inverter circuit controls the current of each phase coil winding of the stator assembly, The motor control circuit board 621 is provided with a PWM input port, and the PWM control signal of the external device is input to the microprocessor after being processed by the interface circuit using the PWM input port. The control method is characterized in that: the motor controller stores multiple groups of motor application parameters, the microprocessor first detects the frequency of the input PWM signal, selects a group of corresponding motor application parameters according to the frequency of the input PWM signal, and then detects the duty cycle of the input PWM signal, and calculates the motor's required operating target value based on the selected group of corresponding motor application parameters and the duty cycle; the motor application parameter refers to the torque application parameter or the air volume application parameter, and the operating target value refers to the torque target value or the air volume target value. It enables the ECM motor to match many air conditioning load models, greatly reduces the motor part number, and brings greater convenience to customers.

[0032] The PWM control signal of the external device mentioned above is the PWM control signal output by the air conditioner control mainboard.

[0033] The above-mentioned microprocessor outputs a feedback signal FG through the interface circuit to represent the state of the motor.

[0034] The feedback signal FG is a PWM signal. The feedback signal FG represents different horsepower segments of the motor through PWM signals of different frequency segments.

[0035] The feedback signal FG is a PWM signal that feeds back the rotational speed, and outputs a square wave PWM signal with a duty cycle of 50%. The frequency f of the square wave PWM signal with a duty cycle of 50% has a fixed corresponding relationship with the rotational speed.

[0036] The feedback signal FG is a PWM signal that feeds back the actual current or power of the motor, and outputs a square wave PWM signal with a duty cycle of 50%. The frequency f of the square wave PWM signal with a duty cycle of 50% has a fixed corresponding relationship with the actual current or power of the motor.

[0037] The above-mentioned multiple groups of motor application parameters refer to at least 3 groups, and each group of motor application parameters includes a maximum value and a minimum value of the motor application parameters.

[0038] The above-mentioned selection of a corresponding motor application parameter according to the frequency of the input PWM signal is the air volume application parameter. The air volume application parameter includes the maximum air volume Qmax and the minimum air volume Qmin. The duty cycle of the input PWM signal is Duty. Then any target air volume:

[0039] Qn = Qmin+(95%-Duty)*(Qmax-Qmin) / (95%-5%).

[0040] After obtaining any target air volume Qn, the motor bus power calibration value Power_goal corresponding to any target air volume is calculated as Power_goal = K0 + K1*Qn + K2*N + K3*Qn*N + K4*N*N; wherein K0, K1, K2, K3, K4 are air volume model function calculation coefficients, N represents the speed, each set of air volume application parameters corresponds to a set of air volume model function calculation coefficients, and the air volume model function calculation coefficients are also stored in the motor controller.

[0041] The above-mentioned motor real-time power Power_actual=Vdc*Idc, where Vdc is the bus voltage and Idc is the bus current. By comparing the motor bus power calibration value Power_goal and the motor real-time power Power_actual, the target speed is continuously adjusted to achieve dynamic balance, and the desired target air volume can be output.

[0042] The input PWM signal has two main characteristics: duty cycle and frequency. The technical solution of the present invention uses an adjustable duty cycle to control target torque or target air volume in different ranges; and uses an adjustable frequency to select different constant torque or constant air volume application parameters. The following takes the ECM motor with constant air volume control as an example.

[0043] 1. The motor detection defines the PWM frequency range, and the appropriate tolerance can be given according to the actual accuracy. This time it is + / -3%

[0044] Air volume application parameter group 1 (air volume range 200CFM-1200CFM) is represented by G1: 80HZ+ / -3%,

[0045] Air volume application parameter Group 2 (air volume range 400CFM-1400CFM) is represented by G2: 90HZ+ / -3%;

[0046] Air volume application parameter group 3 (air volume range 500CFM-1600CFM) is represented by G3: 100HZ+ / -3%;

[0047] Air volume application parameter Group 4 (air volume range 600CFM-1800CFM) is represented by G4: 110HZ+ / -3%;

[0048] Air volume application parameter group 5 (air volume range 800CFM-2200CFM) is represented by G5: 120HZ+ / -3%;

[0049] The sixth group of air volume application parameters is represented by G6: 130HZ+ / -3%;

[0050] The nth group of air volume application parameters is represented by Gn: nHZ+ / -3%;

[0051] …

[0052] The air volume model function coefficients K0, K1, K2, K3, and K4 required for calculating each set of air volume application parameters are as follows:

[0053]

[0054] The following takes the first group of air volume application parameters as an example: After knowing that the air volume range is 200-1200CFM according to the PWM frequency, any target air volume:

[0055] Qn = 200+(95%-Duty)*(1200-200) / (95%-5%)----Formula 1

[0056] It is known that: 95% corresponds to the maximum air volume, and 5% corresponds to the minimum air volume;

[0057] Then the bus power calibration value corresponding to any target air volume is

[0058] Power_goal= K0 + K1*Qn + K2*N + K3*Qn*N + K4*N*N----Formula 2

[0059] Based on the 5 air volume coefficients selected in Group 1 above;

[0060] Compare the motor bus power calibration value Power_goal and the motor real-time power Power_actual, and continuously adjust the target speed. After achieving dynamic balance, the desired target air volume can be output.

[0061] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited thereto. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention are all equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A novel PWM control method for an ECM motor, the ECM motor comprises a motor controller and a motor monomer, the motor monomer comprises a stator assembly, a rotor assembly and a housing assembly, the stator assembly is mounted on the housing assembly, the stator assembly and the rotor assembly are magnetically coupled, the motor controller comprises a motor control circuit board, the motor control circuit board is provided with a microprocessor, an inverter circuit and an interface circuit, the microprocessor controls the inverter circuit, the inverter circuit controls the current of each phase coil winding of the stator assembly, a PWM input port is set on the motor control circuit board, the PWM control signal of the external device is input to the microprocessor after being processed by the interface circuit using the PWM input port, and the method is characterized in that: The control method is to store multiple groups of motor application parameters in the motor controller, the microprocessor first detects the frequency of the input PWM signal, selects a group of corresponding motor application parameters according to the frequency of the input PWM signal, and then detects the duty cycle of the input PWM signal, and calculates the required operation target value of the motor based on the selected group of corresponding motor application parameters and the duty cycle; the motor application parameters refer to torque application parameters or air volume application parameters, and the operation target value refers to torque target value or air volume target value; The multiple groups of motor application parameters refer to at least 3 groups, each group of motor application parameters includes the maximum value and the minimum value of the motor application parameters, and the required running target value of the motor is calculated based on selecting a corresponding group of maximum value, minimum value and duty cycle of the motor application parameters.

2. The novel PWM control method for an ECM motor according to claim 1, characterized in that: The microprocessor outputs a feedback signal FG through the interface circuit to represent the state of the motor.

3. The novel PWM control method for an ECM motor according to claim 2, characterized in that: The feedback signal FG is a PWM signal, and the feedback signal FG represents different horsepower segments of the motor through PWM signals of different frequency segments.

4. The novel PWM control method for an ECM motor according to claim 2, characterized in that: The feedback signal FG is a PWM signal that feedbacks the rotational speed, and the output duty cycle is a 50% square wave PWM signal. The frequency f of the 50% square wave PWM signal has a fixed corresponding relationship with the rotational speed.

5. The novel PWM control method for an ECM motor according to claim 2, characterized in that: The feedback signal FG is a PWM signal that feeds back the actual current or power of the motor, and outputs a square wave PWM signal with a duty cycle of 50%. The frequency f of the square wave PWM signal with a duty cycle of 50% has a fixed corresponding relationship with the actual current or power of the motor.

6. A novel PWM control method for an ECM motor according to claim 1 or 2 or 3 or 4 or 5, characterized in that: According to the frequency of the input PWM signal, a set of corresponding motor application parameters is selected, which is the air volume application parameter. The air volume application parameter includes the maximum air volume Qmax and the minimum air volume Qmin. The duty cycle of the input PWM signal is Duty. Then any target air volume: Qn = Qmin+(95%-Duty)*(Qmax-Qmin) / (95%-5%).

7. The novel PWM control method for an ECM motor according to claim 6, characterized in that: After obtaining any target air volume Qn, the motor bus power calibration value Power_goal corresponding to any target air volume is calculated = K0 +K1*Qn + K2*N + K3*Qn*N + K4*N*N; Among them, K0, K1, K2, K3, and K4 are the calculation coefficients of the air volume model function, N represents the rotational speed, and each set of air volume application parameters corresponds to a set of air volume model function calculation coefficients. The air volume model function calculation coefficients are also stored in the motor controller.

8. The novel PWM control method for an ECM motor according to claim 7, characterized in that: The motor real-time power Power_actual=Vdc*Idc, where Vdc is the bus voltage and Idc is the bus current. Compare the motor bus power calibration value Power_goal and the motor real-time power Power_actual, and continuously adjust the target speed. After reaching a dynamic balance, the desired target air volume can be output.

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