INTERFACE CIRCUIT AND ELECTRICAL APPLIANCE SYSTEM COMPRISING THE SAME

Abstract

An interface circuit, including: a micro control unit (MCU), an isolated power supply, and a signal isolating circuit. The MCU, the isolated power supply, and the signal isolating circuit are integrated on a circuit board. The output end of the isolated power supply supplies power for circuits. The input end of the isolated power supply is connected to an external input power supply. The A/D conversion input port of the MCU is connected to the analog voltage signals. The MCU is configured to convert the analog voltage signals into pulse width modulation (PWM) signals or variable frequency signals with certain duty cycles, and output the PWM signals or the variable frequency signals to the input end of the signal isolating circuit. The signal isolating circuit is configured to output the PWM signals or the variable frequency signals with certain duty cycles.

Claims

1. An interface circuit, comprising: a micro control unit (MCU); an isolated power supply; and a signal isolating circuit; wherein the MCU, the isolated power supply, and the signal isolating circuit are integrated on a circuit board; an output end of the isolated power supply supplies power for circuits; an input end of the isolated power supply is connected to an external input power supply; an A/D conversion input port of the MCU is connected to analog voltage signals; the MCU is configured to convert the analog voltage signals into pulse width modulation (PWM) signals or variable frequency signals, and output the PWM signals or the variable frequency signals to an input end of the signal isolating circuit; and the signal isolating circuit is configured to output the PWM signals or the variable frequency signals.

2. The interface circuit of claim 1, wherein the circuit board comprises a COM port and an input port of the analog voltage signals; the COM port is a common port; and the analog voltage signals are in a range between 0 and 10 V.

3. The interface circuit of claim 1, wherein the circuit board comprises a PWM signal output port and an input port of the isolated power supply.

4. The interface circuit of claim 2, wherein the circuit board comprises a PWM signal output port and an input port of the isolated power supply.

5. The interface circuit of claim 1, wherein the MCU comprises a signal comparison table with regard to the analog voltage signals and corresponding PWM signals having duty cycles; the MCU generates the PMW signals according to the analog voltage signals passing through the A/D conversion input port by referring to the signal comparison table; and the MCU outputs the PMW signals to the signal isolating circuit.

6. The interface circuit of claim 2, wherein the MCU comprises a signal comparison table with regard to the analog voltage signals and corresponding PWM signals having duty cycles; the MCU generates the PMW signals according to the analog voltage signals passing through the A/D conversion input port by referring to the signal comparison table; and the MCU outputs the PMW signals to the signal isolating circuit.

7. The interface circuit of claim 1, wherein in use, the analog voltage signals are input to the MCU, and the MCU calculates the PWM signals according to a functional relationship F=V/K*100%, and outputs the PWM signals to the signal isolating circuit, wherein K is a proportional coefficient, F is a duty cycle of an output signal, and V is a sampled A/D input voltage.

8. The interface circuit of claim 2, wherein in use, the analog voltage signals are input to the MCU, and the MCU calculates the PWM signals according to a functional relationship F=V/K*100%, and outputs the PWM signals to the signal isolating circuit, wherein K is a proportional coefficient, F is a duty cycle of an output signal, and V is a sampled A/D input voltage.

9. An electrical appliance system, comprising: at least one Electronically Commutated Motor (ECM); and a main control circuit board of electrical equipment; wherein the ECM and the main control circuit board are connected to an AC input power supply; the ECM and the main control circuit board are connected to independent grounding wires; the main control circuit board is configured to output between 0 and 10 V analog voltage signals to control speed of the ECM; the ECM is connected to the main control circuit board via an interface circuit; the interface circuit comprises a micro control unit (MCU), an isolated power supply, and a signal isolating circuit; the MCU, the isolated power supply, and the signal isolating circuit are integrated on a circuit board; an output end of the isolated power supply supplies power for circuits; an input end of the isolated power supply is connected to an output end of a power supply of the ECM; an A/D conversion input port of the MCU is connected to the analog voltage signals; the MCU is configured to convert the analog voltage signals into pulse width modulation (PWM) signals or variable frequency signals, and output the PWM signals or the variable frequency signals to an input end of the signal isolating circuit; and the signal isolating circuit is configured to output the PWM signals or the variable frequency signals to a motor controller of the ECM.

10. The electrical appliance system of claim 9, wherein the ECM comprises the motor controller and a motor body; the motor body comprises a stator assembly, a rotor assembly, and a shell assembly; the stator assembly and the rotor assembly are disposed inside the shell assembly; the stator assembly comprises a stator core and a coil winding wound around the stator core; the rotor assembly comprises a rotor core and a permanent magnet sheathed in the rotor core; the motor controller comprises a control circuit board; the control circuit board is provided with a microprocessor, an inverter circuit, a detecting unit of operation parameter of the motor, and a power circuit; an input end of the power circuit is connected to the AC input power supply; output ends of the power circuit supply power for the circuits; the detecting unit of the operation parameter of the motor transmits motor operation data to the microprocessor; an output end of the microprocessor is connected to an input end of the inverter circuit; an output end of the inverter circuit is connected to the coil winding wound around the stator core; the PMW signals or the variable frequency signals output from the signal isolating circuit are directly transmitted to an input end of the microprocessor; and one output end of the power circuit is connected to the input end of the isolated power supply.

11. The electrical appliance system of claim 9, wherein the circuit board comprises a COM port and an input port of the analog voltage signals; the COM port is a common port; the circuit board further comprises a PWM signal output port and an input port of the isolated power supply; and the analog voltage signals are in a range between 0 and 10 V.

12. The electrical appliance system of claim 10, wherein the circuit board comprises a COM port and an input port of the analog voltage signals; the COM port is a common port; the circuit board further comprises a PWM signal output port and an input port of the isolated power supply; and the analog voltage signals are in a range between 0 and 10 V.

13. The electrical appliance system of claim 9, the main control circuit board of electrical equipment is a main control circuit board of air conditioning equipment, a main control circuit board of stove, a main control circuit board of washing machine, or a main control circuit board of heating, ventilation and air conditioning system.

14. The electrical appliance system of claim 10, the main control circuit board of electrical equipment is a main control circuit board of air conditioning equipment, a main control circuit board of stove, a main control circuit board of washing machine, or a main control circuit board of heating, ventilation and air conditioning system.

15. The electrical appliance system of claim 11, wherein the signal isolating circuit is an optically coupled isolator.

16. The electrical appliance system of claim 12, wherein the signal isolating circuit is an optically coupled isolator.

17. The electrical appliance system of claim 9, wherein the MCU on the circuit board of the interface circuit comprises a signal comparison table with regard to the analog voltage signals and corresponding PWM signals having duty cycles; the MCU generates the PMW signals according to the analog voltage signals passing through the A/D conversion input port by referring to the signal comparison table; and the MCU outputs the PMW signals to the signal isolating circuit.

18. The electrical appliance system of claim 10, wherein the MCU on the circuit board of the interface circuit comprises a signal comparison table with regard to the analog voltage signals and corresponding PWM signals having duty cycles; the MCU generates the PMW signals according to the analog voltage signals passing through the A/D conversion input port by referring to the signal comparison table; and the MCU outputs the PMW signals to the signal isolating circuit.

19. The electrical appliance system of claim 9, wherein in use, the analog voltage signals are input to the MCU on the circuit board of the interface circuit, and the MCU calculates the PWM signals according to a functional relationship F=V/K*100%, and outputs the PWM signals to the signal isolating circuit, wherein K is a proportional coefficient, F is a duty cycle of an output signal, and V is a sampled A/D input voltage.

20. The electrical appliance system of claim 9, wherein the isolated power supply and the main control circuit board are common-grounded.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The invention is described hereinbelow with reference to the accompanying drawings, in which:

[0027] FIG. 1 is a connection diagram of an electrical appliance system and an electronically commutated motor in the prior art;

[0028] FIG. 2 is a circuit diagram of an interface circuit for speed regulation in an isolated manner and an electrical appliance system in accordance with one embodiment of the invention;

[0029] FIG. 3 is a diagram showing specific implementation scheme of FIG. 2;

[0030] FIG. 4 is a stereogram of an electronically commutated motor in accordance with one embodiment of the invention;

[0031] FIG. 5 is a stereogram of a motor controller of an electronically commutated motor in accordance with one embodiment of the invention;

[0032] FIG. 6 is a cross-sectional view of an electronically commutated motor in accordance with one embodiment of the invention; and

[0033] FIG. 7 is a circuit diagram an electronically commutated motor in accordance with one embodiment of the invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] For further illustrating the invention, experiments detailing an interface circuit for speed regulation in an isolated manner and an electrical appliance system comprising the same are described below.

[0035] As shown in FIGS. 2-3, an electrical appliance system comprises at least one Electronically Commutated Motor (ECM) and a main control circuit board of electrical equipment. The ECM and the main control circuit board are connected to an AC input power supply. The ECM and the main control circuit board are connected to independent grounding wires. The main control circuit board is configured to output between 0 and 10 V analog voltage signals to control speed of the ECM. The ECM is connected to the main control circuit board via an interface circuit for speed regulation in an isolated manner. The interface circuit for speed regulation in an isolated manner comprises a MCU, an isolated power supply, and a signal isolating circuit. The MCU, the isolated power supply, and the signal isolating circuit are integrated on a circuit board. An output end of the isolated power supply supplies power for circuits. An input end of the isolated power supply is connected to an output end of a power supply of the ECM. An A/D conversion input port of the MCU is connected to analog voltage signals. The MCU is configured to convert the analog voltage signals to PWM signals or variable frequency signals with certain duty cycles, and output the PWM signals or the variable frequency signals to an input end of the signal isolating circuit. The signal isolating circuit is configured to output the PWM signals or the variable frequency signals to a motor controller of the ECM.

[0036] As shown in FIGS. 3-7, the ECM 1 comprises the motor controller 12 and a motor body 11. The motor body 11 comprises a stator assembly 112, a rotor assembly 113, and a shell assembly 111. The stator assembly 112 and the rotor assembly 113 are disposed inside the shell assembly 111. The stator assembly 112 comprises a stator core and a coil winding wound around the stator core. The rotor assembly 113 comprises a rotor core and a permanent magnet sheathed in the rotor core. The motor controller 12 comprises a control circuit board 121. The control circuit board 121 is provided with a microprocessor, an inverter circuit, a detecting unit of operation parameter of the motor, and a power circuit. An input end of the power circuit is connected to the AC input power supply. Output ends of the power circuit supply power for circuits. The detecting unit of the operation parameter of the motor transmits motor operation data to the microprocessor. An output end of the microprocessor is connected to an input end of the inverter circuit. An output end of the inverter circuit is connected to the coil winding wound around the stator core. The PMW signals or the variable frequency signals output from the signal isolating circuit are directly transmitted to an input end of the microprocessor. One output end of the power circuit is connected to the input end of the isolated power supply. The detecting unit of the operation parameter of the motor comprises a measuring circuit of stator positions in FIG. 7. The power circuit outputs three types of supply voltages: DC bus voltage V1, DC voltage V2 of inverter circuit, and DC voltage V3 of the microprocessor of the motor. The DC voltage V3 is output to the input end of the isolated power supply. The circuit structure belongs to the prior art, and no need to illustrate herein. The circuit board of the interface circuit comprises a COM port and an input port of the analog voltage signals. The COM port is a common port. The circuit board further comprises a PWM signal output port and an input port of the isolated power supply. The analog voltage signals are in a range between 0 and 10 V. The isolated power supply and the main control circuit board are common-grounded via the COM port.

[0037] The main control circuit board of electrical equipment is a main control circuit board of air conditioning equipment, a main control circuit board of stove, a main control circuit board of washing machine, or a main control circuit board of heating, ventilation and air conditioning system. The signal isolating circuit is an optically coupled isolator.

[0038] The MCU on the circuit board of the interface circuit comprises a signal comparison table (as shown in Table 1) used for comparing the analog voltage signals with the PWM signals featuring different duty cycles. The MCU generates the PMW signals with certain duty cycles according to the analog voltage signals passing through the A/D conversion input port by referring to the signal comparison table. The MCU outputs the PMW signals with certain duty cycles to the signal isolating circuit.

TABLE-US-00001 TABLE 1 Analog voltage signal Duty cycle of PWM signal 0.1 V  1% 0.2  2% . . . . . . 1.1 V 11% 1.5 V 15% . . . . . . . . . . . . 4.5 V 45% 4.6 V 46% . . . . . . 9.9 V 99%  10 V 100% 

[0039] The analog voltage signals are input to the MCU on the circuit board of the interface circuit, and the MCU calculates the PWM signals with certain duty cycles according to a functional relationship F=V/K*100%, and outputs the PWM signals to the signal isolating circuit. K is a proportional coefficient, and K=10 here, F is a duty cycle of an output signal, and V is a sampled A/D input voltage.

[0040] Unless otherwise indicated, the numerical ranges involved in the invention include the end values. While particular embodiments of the invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects, and therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of the invention.