Spatial Stirling motor under-configuration control system and control method

Abstract

The invention provides a space Stirling motor under-configuration control system and a space Stirling motor under-configuration control method. The space Stirling motor under-configuration control system is composed of a Stirling motor, an AC / DC controller, a balance circuit, a variable load, a temperature sampling circuit, a current sampling circuit and a voltage sampling circuit. The input end of the AC / DC controller is connected with the single-phase output end of the Stirling generator, and the output end of the AC / DC controller is connected with the positive and negative ends of the balancing circuit; the current sampling circuit 1 detects the alternating current value of the Stirling generator, the voltage sampling circuit 1 detects the output alternating voltage value of the Stirling generator, the voltage sampling circuit 2 detects the voltage value at the two ends of the balance circuit, namely the direct current voltage value, and the current sampling circuit 2 detects the total self-flowing current; the temperature sampling circuit comprises a Stirling generator cavity high-temperature end temperature detection device and a Stirling generator cavity low-temperature end temperature detection device which are used for directly detecting absolute values of the high-temperature end and the low-temperature end in a Stirling generator cavity.

Description

Technical Field

[0001] The invention relates to the field of Stirling thermoelectric conversion system control, and in particular to an under-configured control system and a control method for a space Stirling motor. Background Art

[0002] The free piston Stirling generator system is essentially a thermoelectric energy conversion system. The ultimate goal of optimizing its design and using effective control methods to control it is to ensure that it can generate electricity continuously and stably with high efficiency. The power generation performance depends on two main energy conversion components: FPSE and linear generator. Generally speaking, the stable working point of the FPSE oscillation amplitude is usually an unstable equilibrium point within a certain range. In order to ensure that it can oscillate stably with equal amplitude, it is usually necessary to limit and maintain its oscillation amplitude through its own inherent characteristics or introduce a feedback control mechanism from the outside. For linear generators, the electromechanical energy conversion is achieved through the armature reaction of the generator. The existence of the armature reaction under resistive load will cause the armature current of the generator to lag behind the no-load back electromotive force, and the external output electromagnetic power will always be less than the maximum electromagnetic power. It is very necessary to use effective control methods to improve its internal power factor and make full use of the generator capacity to maximize the active power output.

[0003] The unstable oscillation amplitude of FPSE and the non-maximum electromagnetic power of linear generator are inherent defects of Stirling generator. However, in order to ensure the normal operation of free piston Stirling generator, effective control methods can be used to make up for its inherent shortcomings. Therefore, the design of the control system can be realized around the safe and stable oscillation of FPSE and the maximum output of electromagnetic power of linear generator. At the same time, the thermoelectric energy conversion system essentially determines that the control must give priority to ensuring the energy balance of the system.

[0004] Usually, Stirling motor control uses two feedback control methods to achieve FPSE oscillation and motor electromagnetic control. One is the control method of voltage outer loop and current inner loop. The current reference value needs to be measured and calculated by the acceleration sampling circuit, and the outer loop voltage value of this method varies within a certain range. It abandons precise energy balance control, and excess heat will damage the service life of the motor. The other is the control method of displacement outer loop and current inner loop. The outer loop displacement feedback needs to be directly measured by the position sampling circuit or the acceleration sampling circuit, and the energy balance control is achieved through the post-stage circuit control.

[0005] In space applications, due to the limitations of temperature, radiation environment and space volume, it is impossible to install and apply position or acceleration sensors in Stirling motors in some cases. This paper invents an under-configuration control method for free-piston Stirling generators for space, which effectively avoids the above problems. Summary of the invention

[0006] The object of the present invention is to provide a control system and a control method for an under-configured Stirling motor for space use, so as to meet the control requirements of a Stirling generator where position and acceleration sensors cannot be installed in specific space occasions.

[0007] In order to solve the above technical problems, the technical solution of the present invention is: to provide a space Stirling motor under-configuration control system, including a Stirling motor, an AC / DC controller, a balancing circuit, a temperature sampling circuit, a current sampling circuit and a voltage sampling circuit;

[0008] The input end of the AC / DC controller is connected to the single-phase output end of the Stirling generator, and the output end is connected to the positive and negative ends of the balancing circuit; the current sampling circuit detects the AC current value of the Stirling generator, the voltage sampling circuit 1 detects the output AC voltage value of the Stirling generator, and the voltage sampling circuit 2 detects the voltage value at both ends of the balancing circuit; the temperature sampling circuit includes a high-temperature end temperature detection device and a low-temperature end detection device of the Stirling generator cavity, which directly detects the absolute values ​​of the high and low temperature ends in the Stirling motor cavity.

[0009] Furthermore, the current sampling circuit 1 is a bidirectional isolated sampling circuit, the current sampling circuit 2 is a unidirectional isolated current sampling circuit, and the voltage sampling circuit 1 and the voltage sampling circuit 2 are isolated voltage sampling circuits.

[0010] Another technical solution of the present invention provides a method for controlling an under-configuration of a space Stirling motor, which is applied to the above-mentioned under-configuration control system of a space Stirling motor, and comprises the following steps:

[0011] S1, high temperature end temperature T detected by temperature sampling circuit H , low temperature end temperature T L , calculate the high and low temperature difference, amplify it by a specific factor, and calculate it with the heat capacity and mass of the high and low temperature end materials. Then, obtain the absolute value of the theoretical output electric power through the rated thermoelectric efficiency, and perform differential calculation with the detection value of the current sampling circuit 2 amplified by a specific ratio to derive the output DC voltage reference value V p_ref , i.e., temperature ring;

[0012] S2, voltage sampling circuit 2 detects voltage and the reference value V p_ref After PI operation, the AC current amplitude reference value I is obtained. p_ref , i.e., the voltage loop; the current sampling circuit 1 detects the current and performs a PR operation on the current base amplitude standard value, i.e., the current loop, and finally outputs a PWM control signal for controlling the AC / DC controller.

[0013] Furthermore, the balancing circuit is implemented by controlling the DC voltage, the clamping voltage value is positively correlated with the AC voltage detection amplitude, and the optimized ratio value range is 1.2 to 1.6.

[0014] The beneficial effect of the under-configured control system and control method for space Stirling motors provided by the present invention is that the control method does not require the configuration of a displacement sensor, thus avoiding the limitation of high temperature on the use conditions and life of the displacement sensor, and to a certain extent ensuring the design feasibility and service life of the space-compact Stirling motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The invention will be further described below in conjunction with the accompanying drawings:

[0016] Figure 1 This is a block diagram of the Stirling generator under-configuration control system proposed by the present invention;

[0017] Figure 2 A block diagram of the under-configured "three-loop" control strategy for the Stirling generator provided by the present invention. DETAILED DESCRIPTION

[0018] The following is a further detailed description of the space Stirling motor under-configuration control system and control method proposed by the present invention in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become clearer according to the following description and claims. It should be noted that the accompanying drawings are in a very simplified form and use non-precise ratios, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0019] The present invention proposes a generator under-configuration control method, which relies on a hardware system including: an AC / DC controller, a balancing circuit, a variable load, and a temperature, current, and voltage sampling circuit.

[0020] The input end of the AC / DC controller is connected to the single-phase output end of the Stirling generator, and the output end is connected to the positive and negative ends of the balance circuit, which is a conventional connection method;

[0021] The current sampling circuit 1 is a bidirectional Hall sampling circuit, which isolates and detects the output AC current value of the Stirling generator;

[0022] The current sampling circuit 2 is a unidirectional Hall sampling circuit, which detects the total current value of the DC end in isolation;

[0023] The voltage sampling circuit 1 is an isolated sampling circuit to detect the output AC current value of the Stirling generator;

[0024] The voltage sampling circuit 2 is an isolated sampling circuit that detects the voltage at both ends of the balancing circuit and is the direct control target of the balancing circuit;

[0025] The temperature sampling circuit includes a temperature detection device at the high-temperature end and a temperature detection device at the low-temperature end of the Stirling generator cavity, which can feedback the absolute values ​​and differences of high and low temperatures. The core of the present invention is to use the absolute values ​​and differences of high and low temperatures and the thermal characteristic parameters of the corresponding materials to deduce the theoretical output power and voltage of the Stirling generator through a thermal-mechanical-electrical conversion mechanism, and perform multi-loop control by calculating the target power or voltage, while cooperating with the DC side balancing circuit to perform energy balance control.

[0026] Example 1

[0027] like Figure 1 The figure shows the block diagram of the under-configuration control system of the Stirling generator, which includes: a Stirling motor, an AC / DC controller, a balancing circuit, and temperature, current, and voltage sampling circuits. The input end of the AC / DC controller is connected to the single-phase output end of the Stirling generator, and the output end is connected to the positive and negative ends of the balancing circuit. The current sampling circuit 1 detects the AC current value of the Stirling generator, the voltage sampling circuit 2 detects the output AC current value of the Stirling generator, the voltage sampling circuit 1 detects the output AC voltage value of the Stirling generator, and the voltage sampling circuit 2 detects the voltage value at both ends of the balancing circuit; the temperature sampling circuit includes a temperature detection device at the high temperature end of the Stirling generator cavity and a low temperature end detection device, which directly detects the absolute values ​​of the high and low temperature ends in the Stirling motor cavity.

[0028] like Figure 2 The block diagram of the under-configuration control strategy of the Stirling generator in the present invention is shown. The main idea is that when the thermal power is fixed and the Stirling motor is working in rated steady state, there is a regular functional relationship between the temperature difference of the heat exchanger and the power, and the output AC voltage reference value is calculated based on the detected current value, and then the power factor correction control is performed.

[0029] like Figure 2 The high temperature end temperature T detected by the temperature sampling circuit is shown in FIG. H , low temperature end temperature T L , calculate the high and low temperature difference, amplify it by a specific factor, and calculate it with the heat capacity and mass of the high and low temperature end materials. Then, obtain the absolute value of the theoretical output electric power through the rated thermoelectric efficiency, and perform differential calculation with the detection value of the current sampling circuit 2 amplified by a specific ratio to derive the output DC voltage reference value V p_ref , i.e., the temperature loop; detect the DC voltage and the reference value V p_ref After PI operation, the AC current amplitude reference value I is obtained. p_ref , i.e., the voltage loop; the AC current detection value and the current amplitude reference value are calculated, i.e., the current loop, and finally the PWM control signal for controlling the AC / DC controller is output.

[0030] It should be noted that in this control system, the effective load is less than the output power, and the balancing circuit is always in an energy-consuming state to ensure that the thermal power is fixed and the system energy is balanced. Therefore, the balancing circuit is implemented by voltage clamping control, and the clamping voltage value is positively correlated with the AC voltage detection amplitude, and the optimized ratio value range is 1.2 to 1.6.

[0031] The contents not described in detail in this specification belong to the prior art known to those skilled in the art. It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention.

Claims

1. A space-use Stirling motor under-configuration control system, characterized in that: No position sensor or acceleration sensor is required, and the space Stirling motor under-configuration control system is composed of a Stirling motor, an AC / DC controller, a balancing circuit, a temperature sampling circuit, a current sampling circuit and a voltage sampling circuit; The input end of the AC / DC controller is connected to the single-phase output end of the Stirling generator, and the output end is connected to the positive and negative ends of the balancing circuit; the current sampling circuit detects the AC current value of the Stirling generator, the voltage sampling circuit 1 detects the output AC voltage value of the Stirling generator, and the voltage sampling circuit 2 detects the voltage value at both ends of the balancing circuit; the temperature sampling circuit includes a high-temperature end temperature detection device and a low-temperature end detection device of the Stirling generator cavity, which directly detects the absolute values ​​of the high and low temperature ends in the Stirling motor cavity.

2. The space Stirling motor under-configuration control system according to claim 1, characterized in that: The current sampling circuit 1 is a bidirectional isolated sampling circuit, the current sampling circuit 2 is a unidirectional isolated current sampling circuit, and the voltage sampling circuit 1 and the voltage sampling circuit 2 are isolated voltage sampling circuits.

3. A method for controlling an under-configuration of a space Stirling motor, applied to the under-configuration control system of a space Stirling motor as claimed in claim 1 or 2, characterized in that: The steps include: S1, high temperature end temperature T detected by temperature sampling circuit H , low temperature end temperature T L , get the high and low temperature difference T D After the three are functionally calculated with system parameters (including real-time thermal power, motor BL number, resonant frequency and rated thermoelectric conversion efficiency), the relative number of the theoretical maximum output electric power is obtained, and then the DC side power obtained by the DC voltage and current detection value is PID calculated to derive the output AC voltage reference value V p_ref , i.e., the temperature power loop; S2, detection voltage and reference value V p_ref After PI operation, the current reference value I is obtained. p_ref , i.e., the voltage loop; the detected current and the current reference value are subjected to P operation, i.e., the current loop, and finally the PWM control signal for controlling the AC / DC controller is output.

4. The space Stirling motor under-configuration control system as claimed in claim 3, characterized in that: The balancing circuit is realized by controlling the DC voltage, and the clamping voltage value is consistent with the output AC voltage reference value V derived according to claim 3. p_ref There is a positive correlation.

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